The epidemiology of rotavirus gastroenteritis was studied in the Matsuyama district from January to May 1988. Among strains of rotaviruses detected 46 showed the group C‐specific PAGE pattern of virus RNA. Group C rotavirus gastroenteritis occurred following an epidemic of group A rotavirus infection, primarily in children aged 4–7 years but rarely in those aged 0–1 years. This was seriologically confirmed after the epidemic. Unlike the previous strains detected in Matsuyama in 1985–1986, PAGE of the RNA showed arrangement of the 5th, 6th and 7th segments at similar intervals, suggesting virologic variation. The symptoms of fever, diarrhea and vomiting were milder than in group A rotavirus infection used as a