This paper examines the farm-retail price spread for lamb from monthly UK data for 1979-1993. Using cointegration, it examines seasonal patterns in producer and retail prices and seeks to identify a long-run relationship between them. Results show that a long-run relationship exists, and that the direction of Granger-causality is from retail to producer prices. Lamb prices are therefore set in the retail market. Results also show that there is a structural break in the relationship in January 1990 when the price increases; this coincides exactly with a change in policy.