Objective To investigate antibiotic prescribing patterns by general dental practitioners (GDPs) in the Greater Glasgow Health Board Area, Scotland. Study design A 10% sample of prescriptions were selected at random from 35, 545 prescriptions written by GDPs over a 6-month period. Main outcome measures Absolute and relative frequencies were used to describe the different classes of antibiotics used and the variations in prescribing practice. Results GDPs prescribed a wide range of antibiotics. Seventeen different antibiotics were prescribed with amoxycillin, metronidazole and penicillin V accounting for almost 90% of the prescriptions. In general the antibiotics were prescribed at the British National Formulary (BNF) recommended doses. There were, however, wide variations in the frequencies and durations of the prescriptions for all antibiotics. Conclusions The present study provides evidence of sub-optimal prescribing of antibiotics by dentists in Scotland, with considerable variation from the recommended frequencies and doses.