Thirty rumens were examined every month from May 1989 to April 1992 to establish seasonal trends of infection and their relationship to the climatic factors caused by Paramphistomum cervi in cattle. The cattle were chosen from three municipalities of the Sierra region in Tabasco: Jalapa, Tacotalpa and Teapa. P. cervi was found throughout the year with prevalence between 3.33 and 96.67%, and with a yearly average of 39.10%. The major period of infection was shown in Jalapa. However, the maximum mean intensity was found in Teapa. The prevalence of the infection in all three sites was similar, showing the regional trend of P. cervi infection. Cattle were infected mainly throughout the rainy and windy seasons, during summer, autumn and at the beginning of winter.