In this study, normal ranges for hematology and serum biochemistry in children aged 1 to 5 years in Uganda were determined. By a cross-sectional study, 1168 children from Iganga, a prospective site for clinical trials in Uganda, were screened. From 1168 households, 460 children were selected for enrollment, while 600 (58%) were excluded because of either a history of fever in the previous 24 hours, presence of asexual malaria parasites in the peripheral blood or presence of fever. Accordingly, 460 children (39.4%) of median age = 3 years were enrolled in the baseline study. While the lower limits of hemoglobin, hematocrit levels, mean corpuscular volume and platelet counts for the Ugandan children were found to be less than conventional reference values of Caucasisan children, the white blood cell count reference values were higher than the international intervals. On the other hand, the upper limits of the reference intervals for serum transaminases, bilirubin, creatinine, urea, total protein and albumin in sera of the Ugandan children were higher than the corresponding values for a Caucasian pediatric population. This study showed that, if hematology test results of the Ugandan children were assessed against “imported” international reference values, up to 44.6% of the study participants would have been excluded from clinical trials or would have been reported as adverse events in such trials. The present study was not only the first report of serum biochemistry reference ranges for children aged one to five years in Uganda but also one of very few such studies in Africa.