THE of penicillin G procaine in oil with 2% aluminum monostearate (PAM) in the treatment of syphilis, and its continued extensive use have justified the early hopes held for it. Although newer preparations such as benzathine penicillin G appear to have certain advantages over the earlier preparation, there is little question of the value of PAM in the management of syphilis. It seems appropriate at this time, therefore, to review the experience of the Venereal Disease Program of the Public Health Service with this preparation. Through the Public Health Service's Venereal Disease Research Laboratory and the patient material made available first at the various rapid treatment centers and later at the prevention and control centers, the Program has had excellent opportunity to study and evaluate PAM. Observation of sufficiently large groups of patients treated by various schedules had enabled it to arrive at valid comparisons of