The hemoglobin (Hb), serum iron (SI), total iron binding capacity (TIBC), transferrin saturation (TS) and serum ferritin (SF) values of 240 apparently healthy children were determined in a prospective cross-sectional study conducted in Port Harcourt, Nigeria. Standard colorimetric and enzyme immunoassay procedures were used for the estimation all variables. The mean values of all parameters in this study population were; Hb (11.2 +/- 1.83 gldl), TIBC (361.4 +/- 245.7 ugldl, log(c) SI (1.807 +/- 0.45), log(c) SF (1.51 +/- 0.47) and TS (29.3 +/- 18.5%). There was an age-dependent statistical significant difference in the Hb, TIBC and TS values (P < 0.01). Sex was not found to exert any significant influence on the parameters except TIBC. TS had the highest sensitivity and efficiency values of 48 and 95%, respectively. Positive predictive value (PPV), likelihood ratio (LR(+)) and post-test probability values were highest with SF (58%, 3.3 and 62.2%, respectively) as a diagnostic indicator. Hb values correlated positively and significantly with TS (P < 0.01), log(c) SI and log(c) SF concentrations (P < 0.05). Log(c) SF also correlated positively and significantly with Hb and TIBC (P < 0.05). The overall prevalence of iron deficiency anaemia among these children was 33.75%. We conclude that there is a high prevalence of iron deficiency anaemia among apparently healthy children under the age of five years in this part of the world and these results may justify the need for the introduction of a broad intervention programme for this highly vulnerable group. This study is also in support of the hypothesis that SF is the best test for diagnosing or excluding iron deficiency anaemia. The combination of SF, Hb and TS determinations may prove more useful in a resource-limited moderate setting.