BACKGROUND: Fetal hemoglobin (HbF) levels in different hemoglobin variants in Osogbo, Nigeria, were estimated using two principal methods of estimation using existing information for HbF concentration and distribution of various hemoglobin variants in the area, as well as diagnosed cases of thalassemia. Two hundred and sixty samples collected from HbSS, HbSC, HbAA, HbAS, and HbAC subjects were analyzed. HbF level and hemoglobin type were determined in this study. METHODS: The hemoglobin type was determined using cellulose acetate electrophoresis at an alka-line pH, and HbF was determined by the acid elution and alkaline denaturation methods. RESULTS: The mean+/-SD of HbF in the respective hemoglobin variants was as follows: HbSS, 2.09+/-1.94%; HbSC, 0.85+/-0.54%; HbAA, 0.69+/-0.46%; HbAS, 0.52+/-0.31%; and HbAC, 0.57+/-0.26%. The mean HbF level across the hemoglobin variants was statistically significant (P<0.05). Investigating the sex distribution of the HbF level in the studied population revealed a slightly higher mean HbF level in females than in their male counterparts. CONCLUSION: Within the study population, the HbF level was found to be highest in HbSS and lowest in HbAS. The two methods of estimating HbF are equally reliable, since there was no significant difference between the results obtained from the two methods.