1. 1. A comparative study of two strains of rats to an EFA deficient diet was conducted. Parameters of insulin status in BHE and Sprague-Dawley rats were measured. No differences in growth were observed. 2. 2. The strains differed in their hepatic and adipose tissue response to insulin stimulation of glucose oxidation and conversion to fatty acids. 3. 3. Hepatic tissue from EFA deficient BHE rats converted more glucose to fatty acid under the influence of insulin than their controls while diet had no effect on glucose oxidation. 4. 4. Hepatic tissue from EFA deficient Sprague-Dawley rats oxidized more glucose than their controls but diet did not affect fatty acid synthesis. 5. 5. A reverse of these strain and diet differences was observed in adipose tissue. 6. 6. These results suggest that the genetic heritage of the rat may determine the type of response to EFA deficiency.