In this pooled analysis of episodic therapy trials, there was a small impact of acyclovir on the proportion of ulcers healed on day 7 and this was more substantial among patients with HSV ulcers, first episode HSV-2 ulcers, small ulcers, and HIV-1 seropositive individuals with CD4 counts between 200 and 500 cells/mm2. This evidence concerns the gene CD4 and ulcer disease.