Penicillin-resistant Staphylococcus aureus is commonly seen in hospital settings. Recent evidence suggests similar trends in community settings. This study was conducted to determine the incidence of nasal carriage and antibiotic sensitivity patterns of S. aureus in non-hospitalized patients from three midwestern family practice offices. The effect of geographic location of the clinics on nasal carriage and antimicrobial sensitivities was investigated. The following participant variables were analyzed to determine their correlation with nasal carriage and penicillin sensitivity patterns: age, sex, last hospitalization, previous antimicrobial usage, patient or family member employment in a health care facility, and the number of household members. Swabs of the anterior nares were collected from 462 ambulatory patients seen at the three family practice offices. Of these patients, 155 (33.5 percent) were shown to be carriers of S. aureus; 89 percent of the S. aureus isolates were resistant to penicillin. Significant numbers of organisms were also found resistant to tetracycline (22 percent) and sulfadiazine (78 percent). No significant correlations were found between the participant variables and the sensitivity of S. aureus to penicillin or carriage of the organism, nor were there any significant differences between clinics. Penicillinase-resistant penicillins and erythromycin are recommended for use in suspected staphylococcal skin infections.