Lasam, officially the Municipality of Lasam (Ibanag: Ili nat Lasam; Ilocano: Ili ti Lasam; Tagalog: Bayan ng Lasam), is a municipality in the province of Cagayan, Philippines. According to the 2024 census, it has a population of 42,042 people.

The town was once a part of the Municipality of Gattaran, that stretches the width of the province and bisected by the Cagayan River. The barangays west of the river was established as the separate town of Lasam in 1950 by Republic Act No. 507. The new municipality of Lasam became part of the Second Legislative District of the Province of Cagayan.

The Municipality of Lasam was named in honor of Honorio Lasam, a former governor of the province of Cagayan.

Lasam was once a part of Gattaran separated from the mother town by the wide Cagayan River with no bridges connecting the communities. As the population increased, the residents of the western part of the town asked to be amalgamated as a separate municipality.

The town was established on June 13, 1950, by Republic Act No. 507 and signed by President Elpidio Quirino. Barrios (barangays) of Gattaran located west of the Cagayan River were formed into the new and regular Municipality of Lasam, with the old site of the Barrio Macatabang as the seat of the government.

The town was officially inaugurated as independent from Gattaran in January 1951. Ignacio Jurado was appointed as its first mayor whose major task was to build the infrastructure of the new independent town of Lasam.

Lasam is situated 87.92 kilometres (54.63 mi) from the provincial capital Tuguegarao, and 573.07 kilometres (356.09 mi) from the country's capital city of Manila.

Lasam is politically subdivided into 30 barangays. Each barangay consists of puroks while some have sitios.