In vitro antimicrobial susceptibilities for 2,832 isolates from nursing home patients in Oklahoma (1992) were compiled retrospectively. An appreciable proportion of antimicrobial resistance was detected for ampicillin, sulfamethoxazole-trimethoprim and ciprofloxacin among gram-negative bacilli. Of 301 Staphylococcus aureus isolates tested, 70% were resistant to methicillin and 72% resistant to ciprofloxacin. Vancomycin resistance occurred in 22% of Enterococcus faecium isolates. These findings herald a high incidence of antimicrobial resistance in nursing home residents.