OBJECTIVE: The purpose of this study was to test the serotype distribution and antibiotic sensitivity patterns of group B Streptococcus from three Ohio regions in comparison to other areas of the United States. STUDY DESIGN: Three hundred forty-nine group B Streptococcus isolates from three Ohio hospitals were serotyped specifically, and disk diffusion was used to determine antibiotic susceptibility. RESULTS: Serotype V was isolated most frequently (27%); major types la, Ib, 11, and III had frequencies of 18%, 9%, 11%, and 17%, respectively. Erythromycin and clindamycin resistance was 12% (n = 200 isolates) and 8% (n = 49 isolates), respectively. CONCLUSION: The prevalence shift of resistant serotype V group B streptococci in Ohio reflects regional increases and suggests that alternative therapies for patients who are allergic to penicillin may be inadequate.