Objective The aim of this study was to examine the association between early dental caries and iron-deficiency anaemia in preschool children. Patients and methods This case–control study included 100 children with early dental caries aged 2–6 years from the outpatient dental clinic, Benha University hospitals, and 50 caries-free healthy age-matched and sex-matched children as a control group. All children were subjected to a full assessment of history, clinical examination, and laboratory investigations in the form of complete blood count, calculation of serum iron, total iron-binding capacity, serum ferritin, and serum albumin. Results Children with early dental caries had significantly lower mean haemoglobin levels (10.01± 0.83 g/dl) than the controls (11.80 ± 0.91 g/dl), lower mean corpuscular volume (72.56± 4.96 fl) than the controls (80.30 ±6.35 fl), lower mean serum iron (0.40± 0.10 lg/ml) than the controls (0.73± 0.23 lg/ml) and lower mean serum ferritin (31.86 ±18.2 ng/ml) than the controls (40.96± 21.1 ng/ml). Clinical manifestations of vitamin A and B deficiency were significantly increased in the patients than in the controls. There were significant negative correlations between haemoglobin, serum iron and serum ferritin levels with the number of affected teeth. Conclusion Early dental caries had an effect on the state of iron in preschool children giving significantly greater odds of iron-deficiency anaemia. Med Res J 13:108–114 c 2014 Medical Research Journal. Medical Research Journal 2014, 13:108–114 Keywords: early caries, iron-deficiency anaemia, preschool children