Due to the insidious nature of infant anaemia, this disorder frequently remains undetected and untreated by health-care workers in resource-poor settings. We assessed the accuracy of a low-cost and simple diagnostic tool, the haemoglobin colour scale (HCS), in estimating haemoglobin (Hb) values in infants between zero and four months of age. In a rural hospital in Zambia, blood samples were analysed for Hb concentration by HCS and HemoCue method. Bland-Altman plots were used to express agreement between the two methods. The mean difference between HCS and HemoCue at birth (n = 94), two months (n = 87) and four months (n = 69) was 0.39, 0.20 and -0.11 g/dL, respectively. Limits of agreement were -2.39 to 1.51, -1.80 to 2.20 and -1.98 to 1.75 g/dL, respectively. Disagreement with HemoCue measurements of more than 2 g/dL was noted in only 4% of all blood samples. We conclude that the HCS provides Hb estimations in infants aged 0-4 months that are sufficiently accurate to improve timely recognition of anaemia in settings where there is no laboratory.