Mutations at five positions in the Plasmodium falciparum multidrug-resistance gene 1 (pfmdr1), initially thought to confer resistance to chloroquine, have been associated with in vitro resistance to amino alcohols and artemisinin derivatives in more recent studies. To assess the possible association between drug resistance phenotype and pfmdrl polymorphisms and establish the baseline pfmdr1 sequence data in Yaoundé, Cameroon, the in vitro drug sensitivity pattern was determined for 64 clinical isolates by isotopic microtest. The pfmdr1 alleles were determined by a polymerase chain reaction and automatic sequencing. A large majority of isolates carried Tyr-86 (88%) and Phe-184 (91%) alleles. With the exception of one isolate with mixed codon 1246, all isolates had wild-type alleles Ser-1034, Asn-1042, and Asp-1246. There was no statistical association between codons 86 and 184 and in vitro response to chloroquine, amino alcohols, and artemisinin derivatives (P > 0.05). Our data do not seem to support the hypothesis that mutations in codons 86 and 184 influence the in vitro response to these drugs. Further monitoring of both in vitro response and pfmdrl polymorphisms is required to evaluate the potential role played by other pfmdr1 alleles in the determination of drug resistance in Africa.