Human fasciolasis is an infection caused by the liver fluke Fasciola hepatica that predominantly affects cattle and sheep, man being an accidental host. The epidemiological situation has changed in the last few years, reporting an increase in the number of new cases in different countries around the world. In the majority of cases, diagnosis of infection in the acute or invasive phase or in chronic or state phase, is difficult because the symptoms of both phases overlap or due to the lack of symptoms or the intermittent elimination of eggs by the adult worm. Determining the phase will depend on clinical suspicion and on the selection of adequate serological and coprological methods in the acute or chronic stages, respectively, as well as determining whether the patient comes from an endemic area. In this study, we reported six cases of patients that were hospitalized at the Arzobispo Loayza Hospital in Lima, Peru, from 1990 to 1999, whose diagnoses were different from the final ones and which evidenced diagnosing problems. The important correlation between the place of origin, the physical and laboratory findings to diagnose this parasitic disease were emphasized.