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The genetic variability of the CYP1A1 I462V polymorphism (CYP1A1*2C) was investigated in four Brazilian populations: three groups of African descent and one group of European descent. The CYP1A1 polymorphism was analyzed by two different procedures, first by the allele-specific polymerase chain reaction (PCR) method and then by the PCR–restricted fragment length polymorphism (PCR-RFLP) method before digestion with BsrDI. The frequency of CYP1A1*2C was 11% in Brazilians of European descent, a frequency that is slightly higher but not statistically different from that observed in European populations. In Brazilians of African ancestry this value was very high (12% to 15%). This allele was not observed in the only two African populations investigated thus far. By themselves, the two factors of interethnic admixture (with populations of European descent and/or Amerindian populations) and genetic drift cannot explain the high values observed here. Our findings suggest that the CYP1A1*2C allele may possibly be present in Africa, but restricted to some ethnic groups not yet investigated. Environmental factors in South America might also have acted as selective factors increasing the CYP1A1*2C gene frequency. Our data also suggest that the CYP1A1*2C allele might possibly have originated in Africa.