On July and August 1997, two 15-year-old mates of a football team of Tongjin Middle School in northern Kyonggi-do, Korea were consecutively diagnosed as vivax malaria by peripheral blood smear. They had no histories of travelling abroad or drug abuse. They witnessed that other mates in the team were ill of fever in the same period. A small survey was therefore undertaken to determine whether vivax malaria was outbroken locally. A total of 57 students of the team living together in a dormitory was examined for history of fever, presence of splenomegaly, blood smear and anti-P. vivax antibody test by immunofluorescent antibody test (IFAT). Except for the above two patients, only one case revealed a marginal titer of IFAT. No other positive findings of vivax malaria were found. In the results of this local survey, no more cases of vivax malaria were revealed except the two sporadic cases.