The present investigation entitled “Heterosis, combining ability and stability analysis studies in Sunflower (Helianthus annuus L.)” was undertaken with objectives: i) To estimate the extent of heterosis for seed yield and yield contributing characters in sunflower. ii) To study the combining ability of parents and hybrids for seed yield and yield contributing characters in sunflower. iii) To study the stability parameters for seed yield and yield contributing characters in sunflower. six CMS lines viz., 234A, 62A, 243A, 2A, 249A and 17A and nine restorers viz., EC-623008, EC-601957, EC-601951, EC-623026, RHA-1-1, RHA-138-2, R-271-1, IR-1-1 and J/6 in line x tester fashion (6 x 9) to obtain 54 F1s in kharif-2016. Total 72 genotypes including 54F1s, 15 parents and 3 checks (LSFH-171, LSFH-35 and S-275) were evaluated during rabi-2016 and kharif- 2017 at two locations i.e. Latur (E1, E3) and Parbhani (E2, E4) thereby in four environments. The observations were recorded on eleven traits viz., days to 50 % flowering, days to maturity, plant height (cm), head diameter (cm), seed filling %, hull content (%), 100 seed weight, volume weight (gm), seed yield/plant (gm), oil content (%) and downy mildew disease reaction. Analysis of variance in individual environment as well as pooled analysis revealed considerable variation among genotypes for all the characters. Magnitude of SCA variance was higher as compared to GCA for all the traits except to 50% flowering and head diameter. These findings indicated the importance of both additive and non-additive components in inheritance of most of the characters Parents 62B, 234B (lines) and R-271-1, EC-601951 (testers) could be rated as potential for early flowering. While, 62B, 234B, 2B and 17B (lines) and IR-1-1, EC-623008, RHA-1-1 and RHA-138-2 were best general combiners for seed yield/plant, oil content, head diameter, hull content, 100 seed weight and volume weight. Crosses 2A X RHA-1-1, 2A X RHA -138-2, 62A X RHA-138-2, 62A X IR-1-1, 234A X IR-1-1 , 17A X RHA-1-1 and 17A X EC-623008 had significant per se performance over checks and were stained with significant SCA for seed yield and some of its component traits. These top five rank crosses for seed yield also identified as best heterotic crosses for seed yield/plant and some of its component traits like, days to 50% flowering, days to maturity, head diameter, seed filling %, 100 seed weight. For oil content, 62A X IR-1-1and 249A X IR-1-1 recorded high heterotic effect with significant per se performance. These promising hybrids were also found to be disease free under high pressure of Plasmopara halstedii i.e. resistant to downy mildew. Significant differences due to genotypes and environments suggested presence of variation for all characters in all four environments. Significant mean squares due to Genotypes x Environment interaction indicated differential response of genotypes to environmental changes. Parents 249B and EC-601951 were found to be stable for seed yield/plant in favorable environments whereas, crosses 62A x RHA-1-1, 62A X IR-1-1, 2A X EC-601957 and 17A X RHA-1-1were stable and indicated greater resistance to environmental changes.