Clomiphene depressed the growth and enhanced clavine production of Claviceps purpurea strains 129,35 and 59. Mycelial content of 18:2 and 16:0 fatty acids decreased, whereas that of 18:1 and 18:0 acids increased. In the mutant strain 59 clomiphene, triadimefon and ergosterol stimulated the impaired function of chanoclavine cyclase. Their effect was counteracted by plant oil. Clomiphene decreased the content of total lipids (44%), triglycerides (32%), sterols (22%) and sterol/phospholipid molar ratio. The PC/PE ratio was 9X increased. Clomiphene and triadimefon enhanced membrane fluidity of protoplasts, ergosterol and oil reverted their effect.