OBJECTIVE: To examine the proposed association between pityriasis rosea and human herpesvirus 7 (HHV-7). DESIGN: A retrospective cross-sectional survey. SETTING: University medical center in Switzerland. PATIENTS: Thirteen patients with pityriasis rosea and 14 persons with normal skin (control subjects). MAIN OUTCOME MEASURES: Detection of HHV-7-specific DNA sequences and antigen (85-kd phosphoprotein [pp85]) by nested polymerase chain reaction and immunohistochemical analysis, respectively. RESULTS: Human herpesvirus 7 DNA sequences and expression of the HHV-7-specific immunodominant pp85 antigen were found in 1 (8%) of 13 lesional skin biopsy specimens of pityriasis rosea. The prevalence of HHV-7 DNA sequences and antigens is even slightly lower in lesional skin of patients with pityriasis rosea than in clinically and morphologically normal skin of 14 control persons, in 2 of whom (14%) HHV-7 DNA sequences and antigens could be detected. CONCLUSION: The low detection rate of HHV-7 DNA sequences and antigens argues strongly against a causative role for HHV-7 in the pathogenesis of pityriasis rosea.