The need to optimise nutrition to promote growth in infants with chronic renal insufficiency (CRI) is well recognised, but there is less enthusiasm for such an approach in older children and those with milder degrees of CRI. Energy intakes and growth outcomes were prospectively monitored over a 2-year period in children aged 2-16 years with differing levels of severity of CRI, as part of their ongoing joint medical/ dietetic care. Children were grouped following [(51)Cr]-labelled EDTA glomerular filtration rate (GFR, ml/min per 1.73 m(2)) estimations, into 'normal' kidney function [GFR >75, mean 106 (SD 19.5), n =58], providing baseline data only, mild (GFR 51-75, n =25), moderate (GFR 25-50, n =21), and severe (GFR <25, n=19) CRI. Children were followed for 2 years, with 51 completing the study (19 mild, 19 moderate, 13 severe CRI), and were excluded if they required dialysis. None received growth hormone. Regular dietary advice was provided and yearly 3-day semi-quantitative dietary diaries and baseline and 6-monthly anthropometric measurements were obtained. Mean height standard deviation score (SDS) was maintained in those with mild and moderate CRI and significantly increased in children with severe CRI [0.1 SDS (0.32 SD), F =9.45, 1 df, P =0.003]. There was a non-significant reduction in energy intake from dietary records overall (median -8.5% estimated average requirement), associated with poor adherence to supplements in severe CRI and under-reporting in the mild group. An increase in height or body mass index SDS, however, was observed in all children who took the supplements as prescribed. A correlation between change in energy intake and change in height SDS was observed in severe CRI ( r(2)=0.58, P =0.011). Regular dietetic advice, with particular attention to adherence to optimise energy intake, may improve growth, irrespective of age and should form an integral part of the clinical care package.