The results of several years of study in Sweden on intercropping in carrots as a method for reducing damage caused by carrot fly,Psila rosae, are evaluated. Lucerne,Medicago littoralis, was used as a living mulch intercrop. The yield decrease due to competition from the intercrop was quantified and weighed against the benefits of the intercrop in terms of reduced damage caused by the carrot fly, soil nitrogen enhancement through N-fixation, and decreased weed germination and development. The negative effects of competition were less pronounced in years with a high carrot fly population. In years when yield losses caused by the fly were low, the competition effect remained. Cultural methods for decreasing competition are discussed.