Deaminations of adenine and adenosine by pattern strains of 24 staphylococcal species, were tested. During 3 hours of incubation of the suspensions of 8 staphylococci with adenine the liberation of ammonia occurred. The same staphylococci accumulated ammonia in the incubation medium with adenosine. The Staphylococcus intermedius PCM 2405 strain as opposite to the Staphylococcus aureus 536 strain in the media with adenine or adenosine accumulated hypoxanthine or inosine, respectively and ammonia. These results indicated that adenine deaminase (adenase) and adenosine deaminase activities were associated with the cells of the Staphylococcus intermedius PCM 2405 strain. Staphylococci were heterogeneous within three species groups with respect to adenine and adenosine deaminations. Adenine and adenosine determinations were absent in staphylococci belonging to the Staphylococcus simulans species group.