In a controlled clinical trial undertaken in ten Italian centres, rifamycin SV was compared to associations of various drugs such as erythromycin, aureomycin, multivitamin preparations, etc, in the treatment of herpes zoster. Up to now 144 patients, suffering from herpes zoster at different localizations, were divided into three groups and randomly given either rifamycin SV by intramuscular injection and topically, or rifamycin SV by injection only, or the routine treatment used at the particular centre in question. To evaluate the effectiveness of the treatments, the presence of subjective and objective symptoms was determined before treatment started and daily thereafter. The duration, in days, of the most important symptoms, such as erythema, vesicles, scabs and pain, was considered for this partial evaluation. All the above-mentioned symptoms constantly showed a shorter duration in the two groups treated with rifamycin SV compared to the group treated with other therapies, with differences as significant on statistical calculation as they were important on the level of a clinical evaluation of the disease's course.