A review was undertaken of 7,521 serum samples that had been tested to detect or confirm the presence of different hepatitis A, B, and delta serologic markers. The sources of the samples included a national reference laboratory, several outbreaks of viral hepatitis in civilian and military populations, and a serologic survey. They were examined using the enzyme-linked immunosorbent assay (ELISA). The prevalence of antibody to hepatitis A virus was very high (means = 92.2%), and it was uniform. Prevalence of hepatitis B markers was more variable and inconsistent; it was high in samples from the jungle region of Peru, where the average prevalence of hepatitis B surface antigen (HBsAg) was 4.9%. Antibodies to delta hepatitis were present in 28.6% of the carriers of HBsAg identified in the outbreaks. All the outbreaks had similarities, including a high, cyclic case-fatality rate associated with the delta virus. Hepatitis A is highly endemic in Peru, while hepatitis B has average endemicity. It will be necessary to do more etiologic diagnosis of cases and conduct more research in order to better understand the epidemiology of viral hepatitis in this country.