Abstract: A field experiment has been conducted at garden lands (Vertic ustochrept) of Agricultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore during Kharif (June to October) season of 2004 to ascertain the optimum nutrient requirement for groundnut+sunflower intercropping system under irrigated conditions with replacement series to enhance the productivity of groundnut+sunflower inter cropping system. Groundnut was raised as main crop and sunflower was planted as intercrop with 3:1 ratio. There were ten treatments viz., control (T1), 100% Recommended Dose of Fertilizers (RDF) to main and inter crops (T2), 100% RDF to main crop+no fertilizer to intercrop (T3), 100% RDF to main crop+100% RDF to intercrop (T4), 100% RDF to main crop+50% RDF of intercrop (T5), T3+50% RDF to intercrop as basal+50% N to intercrop as top dress (T6), T3+50% N to intercrop as basal (T7), T3+100% PK of intercrop as basal+50% N as basal+50% N as top dress (T8), pure crop of sunflower with RDF (T9) and pure crop of groundnut with RDF (T10) were tested in randomized block design with three replications. All the above fertilizer treatments were imposed based on the area. 100% RDF to groundnut (main crop)+100% RDF P and K to sunflower (intercrop)+50% of N basal and 50% of N as top dressing to sunflower increased yield attributes, yield and oil contents of groundnut and sunflower. So, 100% recommended doses of NPK fertilizer to groundnut+100 RDF PK to sunflower with 50% N as basal and 50% (T8) as top dressing will be optimum to realize maximum yield under groundnut+sunflower intercropping system in irrigated conditions.