Progesterone exerts most of its actions through its specific receptors. However, synthetic progestins and progesterone itself may bind with other steroid receptors, thus producing a variety of effects. For instance, some nonsteroid derivatives produce virilizing effects by acting on testosterone receptors. In contrast, other derivatives may inhibit or potentiate the actions of androgens. Similar interactions of progestins with gluco- or mineralocorticoid receptors have been reported. The therapeutic applications of progestins are therefore extremely numerous. An improved knowledge of the mode of action of individual available progestins results in better management of a wide variety of clinical disorders including, amongst others, endometrial pathology, benign breast diseases, hirsutism and acne.