The Cartwright Inquiry was a committee of inquiry held in New Zealand from 1987 to 1988 that was commissioned by the Minister of Health, Michael Bassett, to investigate whether, as alleged in an article in Metro magazine, there had been a failure to treat patients adequately with cervical carcinoma in situ (CIS) at National Women’s Hospital (NWH) by Herbert Green, a specialist obstetrician and gynaecologist and associate professor at the Postgraduate School of Obstetrics and Gynaecology, University of Auckland. The inquiry was headed by District Court Judge Silvia Cartwright, later High Court Justice, Dame and Governor-General of New Zealand. The Report of the Cervical Cancer Inquiry was released on 5 August 1988.

A 1984 medical paper published in Obstetrics and Gynecology by colposcopist Bill McIndoe, pathologist Jock McLean and gynaecologist Ron Jones, who were all employed at NWH and colleagues of Green, as well as statistician Peter Mullins, described an audit of 948 women who had been diagnosed with cervical carcinoma in situ (CIS) at New Zealand's National Women's Hospital from 1955 to 1976. The authors retrospectively divided the women with CIS into two groups: those with normal cytology follow-up at two years after initial management (817) and those who continued to have abnormal cytology (positive smears) (131). Among those who continued to have abnormal cytology, a much higher proportion developed invasive cervical or vaginal vault cancer (22% versus 1.5% over five to 28 years). The authors concluded that CIS of the cervix had significant invasive potential.

Using that paper, the medical experience of one of Green's patients as a case study (under the pseudonym 'Ruth') and interviews with staff, a freelance journalist, Sandra Coney, and an academic, Phillida Bunkle, published an exposé, 'An "unfortunate experiment" at National Women’s Hospital', in Metro Magazine in June 1987. The article alleged that Green was carrying out research on his patients without their knowledge or consent and that since the mid-1960s, he had been withholding conventional treatment from some patients with CIS. Coney and Bunkle took the title of their article from a 1986 letter in the New Zealand Medical Journal by Professor David Skegg, a University of Otago cancer epidemiologist and expert in population screening in which he referred to "the unfortunate experiment at National Women's Hospital" in his reply to Green about the study. The authors claimed that no one could give them an assurance that the study had been stopped. Publication led to such enormous public outrage and concern that within ten days, the Minister of Health, Michael Bassett, established an inquiry.

In June 1966, Green received permission from the NWH's Senior Medical Staff (SMS) and the Hospital Medical Committee (HMC) to undertake a study of following women with CIS (now, together with severe dysplasia, termed Cervical Intraepithelial Neoplasia 3, CIN3) without treatment. Green's proposal stated that all patients with a diagnosis of CIS under the age of 35, with positive smears and no colposcopic evidence of invasive cancer and without a ring or cone biopsy, would be followed. The Minutes recorded that Green stated that 'his aim was to attempt to prove that carcinoma-in-situ is not a pre-malignant disease'. He also said that if at any stage concern was felt for the safety of a patient, a cone biopsy would be performed.

Green published the evolving results of his study in the natural history of CIS in a series of papers from 1966 to 1975. In 1969, he wrote about his methods more clearly than in his proposal: "In 1965 [sic] the SMS of NWH initiated a project under the supervision of the author, for patients up to 35 years of age whose only abnormal finding was positive cervical cytology.... a histological diagnosis was to be established by punch biopsy of the most colposcopically significant area. Provided the biopsy did not remove the entire significant area, or reveal invasive carcinoma, there was to be no further treatment. As of the end of 1967, 33 such patients were studied." Green reported that none of the patients had been subsequently diagnosed with invasive cancer, as of June 1968.  

In 1970, Green published further results and described his study: "The only way to settle finally the problem of what happens to in situ cancer is to follow indefinitely patients with diagnosed but untreated lesions. This is being attempted." Again, he recorded no patients developing invasive cancer. A further paper from 1970 provided mathematical estimates of the invasive potential of CIS by using "follow-up observations on 75 patients who were untreated or incompletely treated". No patients were reported to have developed invasive cancer.

In the last paper, in 1974, Green again described his study: "This series of 750 cases of in situ cervical cancer, and the following of 96 of them with positive cytology for at least two years, represents the nearest approach yet to the classical method of deciding such an issue as the change of one disease state to another – the randomised controlled trial. It has not been randomised and it is not well controlled, but it has at least been prospective." This time, Green reported that 10 cases had apparently progressed to invasion but that only 2 had "no clinical or histologic doubt." [Only one of the patients was under age 35.] He concluded that the present series "offers little proof of the progression hypothesis."

Green published nothing else. A later and separate re-evaluation of the invasive potential of CIS, based on a review of NWH patients' files, was published by McIndoe et al, with very different findings.