The major initial aim of the present study was to explore the possible relationship between the relative weight content of docosahexaenoic acid (C22:6ω3) in phospholipids and the increase in the triglyceride ratios between either palmitoleic and palmitic acids (C16:1ω7/C16:0) or oleic and stearic acids (C18:1ω9/C18:0) found in female rats either exposed for 3 to 7 months to a diet deprived of long-chain polyunsaturated ω3 fatty acids or in second-generation rats also exposed to an ω3 fatty acid-depleted diet. The gender difference in such relationship was also investigated. Although negative correlations between the two variables under consideration were indeed observed in the female, but not male, rats, this situation solely reflected a group effect. Evidence was nevertheless obtained for the coordinated regulation of the two ratios representative of Δ9-desaturase activity in both liver phospholipids and triglycerides. In this respect, the most representative correlation concerned the values of the same ratio in the two lipid classes. A comparable situation was not found in the brain phospholipids of the same female animals. It is proposed that the present study provides leading information in the perspective of a better understanding of factors ruling the Δ9-desaturase-catalyzed interconversion of fatty acids in the liver.