Colombian field isolates of Plasmodium falciparum were analyzed for genetic diversity. Fifty-three samples were collected as thick smears from patients living in PanguÃ, an isolated area with low migration. While the samples were being collected, PanguÃ was experiencing an epidemic outbreak of malaria. The samples were typified using nested polymerase chain reaction (PCR) amplification of block 2 of the merozoite surface protein 1 (MSP1) gene and nested PCR with mutation-specific primers for position 108 of the dihydrofolate reductase enzyme gene. The results for the circulating population of parasites in PanguÃ show low diversity--four allelic forms--using MSP1 as a marker, a fact that contrasts with data reported for certain Asian and African zones. A high percentage of mixed infections was observed, as was high complexity of the infection. No differential distributions were found for any allelic type.