The identified mutations in the pfcrt, dhfr and dhps genes of Plasmodium falciparum show a very high correlation with resistance to chloroquine, pyrimethamine and sulfadoxine, the drugs that are still used as malaria chemoprophylaxis or treatment. We undertook a molecular screening of 82 Polish P. falciparum isolates, mainly imported from different countries of sub-Saharan Africa to assess their molecular drug-resistance profiles. Only 4 isolates showed no mutations in the three analyzed gene fragments. In the remaining isolates from one to six mutations in one or more examined genes were found. Different mutations in the pfcrt, dhfr and dhps genes were found in ca. 76%, 80% and 70% of P. falciparum isolates, respectively. About forty our patients used chloroquine or pyrimethamine + sulfadoxine as malaria chemoprophylaxis and/or antimalarial treatment, but without success. In all but 5 of the P. falciparum isolates obtained from these persons, mutations associated to resistance of the parasite to chloroquine and the antifolate drugs were found.