Imported malaria is one of the perplexing problems in the world. Migrants, either refugees or those looking for better opportunites in life, have contributed to the introduction of malaria to previously free areas. The increased incidence of imported malaria is distinctly attributed to a failure of travellers to take appropriate action to prevent infection. Annually up to 100 cases of malaria are presumed to be imported into Japan and most of these cases are Plasmodium falciparum and P. vivax malaria. The reports of P. malariae malaria cases are very few in Japan. The present paper reports a case of one patient with imported P. malariae malaria infection accompanied with marked hepato-splenomegaly who has come from Nigeria. And this patient was treated with Fansidar® (sulfadoxine-pyrimethamine) and minocycline which were very effective against this infection.