In infants, sleeping metabolic rate (SMR) is used as a proxy for basal metabolic rate (BMR). BMR can be predicted from anthropometry using published equations. Our study was intended to evaluate the ability of these equations to predict measured SMR in infants aged 6 weeks to 12 months. SMR was measured in a mixed longitudinal study using the Douglas bag technique (n = 105). Measured SMR values were compared with BMR predicted from weight (BMR-1) or weight and length (BMR-2). These equations were not successful in predicting SMR in this age group. Percentage error of predicted BMR was related to infant weight (BMR-1: r = 0.26; p < 0.005; BMR-2: r = 0.18; p < 0.06). Alternative logarithmic equations were derived from this study (R = 0.84-0.87; SEE = 0.159-0.168). We conclude that the new equations, relating to contemporary infants, are more suitable but actual measurements remain preferred.