Erotic lactation (clinically known as milk fetishism or lactophilia) is sexual arousal from breastfeeding or sucking on a female breast. It may occur in the context of an adult nursing relationship (ANR). The clinical terms are classified as paraphilias in systems such as the ICD-10 and DSM-IV, but when practiced consensually between adults, erotic lactation can serve erotic, emotional, or nurturing purposes without being considered a disorder.

Breasts, and especially nipples, are highly erogenous zones, for both men and women. Nipple and breast stimulation of women are a near-universal aspect of human sexuality, though men's nipples are not as sexualized. Humans are the only primates whose female members have permanently enlarged breasts after the onset of puberty; the breasts of other primate species are enlarged only during pregnancy and nursing. One hypothesis postulates that the breasts grew as a frontal counterpart to the buttocks as primates became upright to attracting mates, a model first developed in 1967. Other hypotheses include that by chance breasts act as a cushion for infant heads, are a signal of fertility, or elevate the infant's head in breastfeeding to prevent suffocation. Paradoxically, there is even a school that believes that they are an evolutionary flaw, and can actually suffocate a nursing infant. The association of pleasure and nutrition holds true as well for the lips, also erogenous zones, where pleasure may have led to "kiss feeding", in which mothers chew food before passing it on to the child.

Unintended milk flow (galactorrhea) is often caused by nipple stimulation and it is possible to reach normal milk production exclusively by suckling on the breast. Nipple stimulation of any sort is noted in reducing the incidence of breast cancer.

Certain individuals may experience a loss of arousal while breastfeeding, making the idea of lactation with a partner non-erotic for them. This can stem from physical causes, such as soreness, or psychological factors, such as feeling conflicted about their breasts being used for purposes other than nursing an infant.

Because female breasts and nipples are generally regarded as an important part of sexual activity in most cultures, it is not uncommon that couples may proceed from oral stimulation of the nipples to actual breastfeeding. In its March 13, 2005, issue, the London weekly newspaper The Sunday Times reported a commercial survey of around 2000 British men, carried out by the infant formula manufacturer Cow & Gate, which indicated that in a third of all couples, the male partner had tasted their partner's breast milk. The men regularly said their motive was an emotional desire to increase their role in infant rearing.

Erotic lactation is sometimes seen as a kink. Those who partake in it can become sexually aroused by seeing a person lactate, having sex with a lactating person or sucking on their breasts.

The breasts have two main roles in human society: nutritive and sexual. Breastfeeding in general is considered by some to be a mild form of exhibitionism, especially in Western societies (see breastfeeding in public). Breastfeeding parents have faced legal ramifications for nursing their children into toddler-hood or in public, or for photographing themselves while nursing.

Researcher Nikki Sullivan, in her book A Critical Introduction to Queer Theory, calls erotic lactation a manifestation of "Queer." She defines Queer as an ideology; that is, as a "sort of vague and indefinable set of practices and (political) positions that has the potential to challenge normative knowledges and identities." Drawing on a statement of David Halperin, she continues "since queer is a positionality rather than an identity in the humanist sense, it is not restricted to gays and lesbians but can be taken up by anyone who feels marginalized as a result of their sexual practices." The heteronormative profile of breastfeeding assumes certain norms: