Background: Worldwide the commonest cause of anaemia is inadequate nutritional supply manifest as iron deficiency. Iron deficiency affects 25% of the world’s population and up to 50% in the developing world. Most susceptible are women of child bearing age and infants. In pregnancy most iron deficiency is detected when there is already resultant anaemia by measuring the haemoglobin content. It is important to develop a tool that could pick out women who are iron deficient before anaemia ensues. This study aims to determine the predictive ability of red cell mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV) in screening for iron deficiency in pregnancy. Objectives: This study was conducted to determine the diagnostic reliability of MCV and MCH in screening for iron deficiency among pregnant women with normal haemoglobin. The study also determined the prevalence of iron deficiency in the pregnant population without anaemia. Study design: This was a descriptive cross-sectional study. Methods: One hundred and fifty five pregnant women presenting to the antenatal clinic at the Aga Khan University Hospital, Nairobi, before 20 weeks gestational age were enrolled. Blood samples were analysed for haemoglobin, red cell indices and serum ferritin levels. Those whose haemoglobin was above 10.5g/dL underwent correlation of MCH and MCV against serum ferritin. The serum ferritin below 15ng/ml was considered representative of iron deficiency. The cut-off points for MCV and MCH were 80fL and 27pg respectively values below which were considered to represent iron deficiency. Results and analysis: The prevalence of anaemia in the study population was found to be 8%. Of the women whose haemoglobin was normal (above 10.5g/dL) the prevalence of iron deficiency as measured by serum ferritin was 31.5%. MCH had a sensitivity of 77.8% (95% CI 66.3 to 86.6) and a specificity of 68.4% (95% CI 63.1 to 72.4). The MCV had a sensitivity of 46.7% (95% CI 35.8 to 56.8) and a specificity of 84.7% (95% CI 79.7 to 89.2). Both tests were useful as negative predictors when considered in the screening for iron deficiency in pregnancy. Conclusion: The prevalence of iron deficiency is high among pregnant women who have normal haemoglobin values. The red cell indices, MCH and MCV have some value in assuring that iron deficiency is unlikely when they are normal. This might be important in clinical units that practice selective supplementation with haematinics in the obstetric population so as to avoid unnecessary iron therapy which has