Market Rasen is a market town and civil parish within the West Lindsey district of Lincolnshire, England. The River Rase runs through it east to west, approximately 13 miles (21 km) north-east from Lincoln, 18 miles (29 km) east from Gainsborough, 14 miles (23 km) west of Louth, and 16 miles (26 km) south-west from Grimsby. It lies on the main road between Lincoln and Grimsby, the A46, and is famous for its racecourse. In 2001, the town had a population of 3,200. In the 2011 census, the population of the civil parish was 3,904.

A market town is a settlement most common in Europe that obtained by custom or royal charter, in the Middle Ages, a market right, which allowed it to host a regular market; this distinguished it from a village or city. In Britain, small rural towns with a hinterland of villages are still commonly called market towns, as sometimes reflected in their names.