Method of controlling male fertility

A method of controlling male fertility in warm-blooded animals comprising orally administering to male warm-blooded animals an amount of a compound selected from the group consisting of a compound of the formula ##STR6## wherein R.sub.1 and R.sub.2 taken together with the nitrogen form a saturated 5 to 6 ring heterocycle optionally containing a second nitrogen or oxygen in the ring, R.sub.3 is .alpha.- or .beta.-methyl, n is an integer from 2 to 10, R.sub.4 and R.sub.5 together are .dbd.O or R.sub.4 is selected from the group consisting of hydrogen, --OH and acyloxy of an organic carboxylic acid of up to 12 carbon atoms and R.sub.5 is selected from the group consisting of hydrogen, --OH, acyloxy of an organic carboxylic acid of up to 12 carbon atoms and alkyl, alkenyl and alkynyl of up to 8 carbon atoms, R.sub.6 and R.sub.7 together are .dbd.O or are individually selected from the group consisting of hydrogen, --OH and acyloxy of an organic carboxylic acid of up to 12 carbon atoms or R.sub.5 and R.sub.6 form a double bond and R.sub.4 and R.sub.7 are hydrogen and their non-toxic, pharmaceutically acceptable acid addition salts in an amount sufficient to control male fertility by affecting the fertilizing power of the spermatozoids without hormonal activity.