A male sterile plant was observed in a sunflower (Helinnthus annus L) population raised from a 12-day-old immature embryo culture of cultivar Modern. This plant was crossed with the parental line. The Ft was fertile and the F2 segregated in the ratio of 3 fertile: 1 sterile, indicating that male sterility was governed by a single recessive nuclear gene. The monogenic recessive nature was confirmed by a test cross, where it segregated in the ratio of 1 fertile: L sterile. With the Cultivar Modern, being early and dwarf, male sterility could be effectively exploited for developing early, dwarf, and semidwarf lines/hybrids.