There is insufficient evidence concerning the efficacy of antiviral treatment of Bell's palsy (BP). We therefore compared the efficacy of prednisone and famciclovir to prednisone treatment alone in BP. A total of 167 consecutive patients with untreated acute BP were included. Severity of BP was evaluated using the House-Brackmann scale (HBS) and virus antibody tests (herpes simplex virus, varicella zoster virus) were performed. Patients admitted on even dates were treated with prednisone ("P group") and patients admitted on odd dates were treated with prednisone and famciclovir ("P+F group"). 117 patients completed the follow-up after 3 months or later (67 P/51 P+F). While most patients showed at least partial recovery with both treatment types, improvement of at least 4 grades in the HBS was more common in the "P+F group" (29.4 % vs. 11.9 %), whereas smaller changes of less than 3 grades were more common in the "P group" (29.9 % vs. 17.6 %; Chi-square test, p = 0.02). Patients with complete BP (HBS grade of 5 or 6) had significantly better chances of reaching normal function if treated with famciclovir additionally instead with prednisone alone (73.7 % vs. 47.1 %; Cochran-Armitage trend test, p = 0.03). These results suggest that the combined treatment of famciclovir and prednisolone should be considered (at least) in patients with severe BP.