Interleukin-1, tumour necrosis factor-α and interleukin-6 are considered to be major mediators of inflammatory processes. In the present study, cytokine gene transcription was detected by the polymerase chain reaction technique during cutaneous and intraperitoneal infection with herpes simplex virus-1. Epidermal cell suspensions obtained from mice infected with herpes simplex virus-1 in the ear pinna were enriched or depleted in Langerhans cells by immunomagnetic fractionation. Herpes simplex virus-1 infection in the skin was found to induce interleukin-1β, tumour necrosis factor-α and interleukin-6 gene transcription in keratinocytes at 24 hours post-infection. Gene transcription declined by 48 hours post-infection. Induction of interleukin-1β and tumour necrosis factor-α but not of IL-6 gene transcription was detected in Langerhans cells obtained from infected mice at 24 hours post-infection. In order to study cytokine gene transcription during intraperitoneal infection with herpes simplex virus-1, peritoneal exudate cells were obtained from infected mice. Maximal levels of interleukin-1β, tumour necrosis factor-α, and interleukin-6 mRNA were found in peritoneal exudate cells 6 hours after infection. RNA transcription declined at 24 hours post-infection and was no longer detectable at 48 hours post-infection. Since the higher susceptibility of newborn mice to intraperitoneal herpes simplex virus-1 infection has been suggested to be related to defective cytokine production, cytokine gene transcription was compared in peritoneal exudate cells obtained from infected newborn and adult mice. No significant differences in interleukin-1β, tumour necrosis factor-α and interleukin-6 gene expression were observed in peritoneal exudate cells obtained from newborn mice as compared with adult mice. In conclusion, cutaneous and intraperitoneal infection with herpes simplex virus-1 induces interleukin-1β, tumour necrosis factor-α and interleukin-6 gene transcription in epidermal and peritoneal exudate cells.