Suspensions of Staphylococcus aureus Foggi strain were exposed to nitrosoguanidine and screened on deoxyribonucleic acid-acridine orange-agar plates for loss of extracellular nuclease activity. All nuclease-deficient mutants lacked cross-reacting material when tested with antinuclease antibody. Coagulase and beta-hemolysin were also lost in nuclease-deficient mutants, and all three enzyme functions were regained together upon reversion with ethyl methane sulfonate. These observations are consistent with the suggestion that the synthesis or the release, or both the synthesis and release, of certain extracellular enzymes may be subject to coordinated control mechanisms.