Foscarnet 0.3% cream was compared with placebo in a randomised double-blind study. The objective was to investigate the therapeutic efficacy and safety in men with recurrent genital herpes simplex virus (HSV) infections. A total of 51 patients were selected, of which 49 (25 treated with foscarnet) were valid for efficacy analysis. Different variables were analysed including the time to healing, alleviation of symptoms, side effects and the results of viral cultures. The median time to healing was 4 days in foscarnet treated patients compared to 5 days in placebo controls. The difference was not statistically significant (p = 0.22). However, foscarnet alleviated the severity of pain and also significantly reduced the median time to abolition pain to 3 days from 6.6 days in placebo treated patients (p = 0.0028). An antiviral effect of foscarnet was evident. The percentage of positive viral cultures found after starting treatment was 15% in the foscarnet-treated group compared to 44% in the placebo-treated group (p = 0.01). Treatment with foscarnet cream was not associated with any significant side effects.