In contrast to oil seeds, potato (Solanum tuberosum L.) is characterized by a high amount of starch stored in the tubers. To assess the capacity for oil synthesis in potato tubers, the changes in lipid content and flux into lipid synthesis were explored in transgenic potatoes altered in carbohydrate or lipid metabolism. A strong decrease in the amount of starch observed in antisense lines for ADP-glucose pyrophosphorylase or plastidic phosphoglucomutase had no effect on storage-lipid content. Similarly, potato lines over-expressing the Arabidopsis thaliana (L.) Heynh. plastidic ATP/ADP transporter that contained an increased amount of starch were not altered in oil content, indicating that the plastidic ATP level is not limiting fatty acid synthesis in potato tubers. However, over-expression of the acetyl-CoA carboxylase from Arabidopsis in the amyloplasts of potato tubers led to an increase in fatty acid synthesis and a more than 5-fold increase in the amount of triacylglycerol. Taken together, these data demonstrate that potato tubers have the capacity for storage-lipid synthesis and that malonyl-CoA, the substrate for elongation during fatty acid synthesis, represents one of the limiting factors for oil accumulation.