Plant storage oils are of major commercial importance, yet our understanding of the regulation and control of their synthesis is poor. The control of lipid biosynthesis fluxes in the mesocarp of oil palm (Elaeis guineensis) was studied using modular (top-down) metabolic control analysis (TDCA). This allowed us to determine the relative contribution of two groups of reactions, fatty acid formation (Block A) and lipid assembly (Block B), to the control structure of overall pathway to triacylglycerol. The pathway was manipulated in two ways. Single manipulation involved the addition of oleate which inhibited fatty acid formation in Block A and stimulated lipid assembly in Block B. In double manipulation experiments, cerulenin was used in inhibition of Block A and Block B was inhibited by bromooctanoate. Single manipulation-TDCA revealed that the group flux control coefficient for fatty acid synthesis was 0.65 and 0.35 for lipid assembly. Double manipulation- TDCA has a value of 0.6 for fatty acid synthesis and 0.4 for lipid assembly. Taken together, these data showed that under our experimental conditions, about 60%-65% of the total metabolic flux control lay in the fatty acid synthesis group of reactions. Nevertheless because both parts of the lipid biosynthesis pathway exert significant flux control, we suggest strongly that manipulation of single enzyme will not affect the product yield appreciably.