Baseline and follow-up data from 4 samples of immunocompetent patients with herpes zoster who participated in clinical trials of the antiviral agent famciclovir were examined (N = 1778). In both univariate and multivariate analyses, severe rash (ie, >50 lesions, defined as papules, vesicles, or crusted vesicles) was significantly associated with older age, male sex, severe pain, primary involvement of nontrigeminal dermatomes, and a greater number of affected dermatomes. In addition, severe rash predicted the presence of pain 3 months later. The results indicate that severe rash is more common in patients with herpes zoster who are older and who have more severe acute pain and confirm that severe rash is a risk factor for prolonged pain.