Lead is suspected to contribute to the progression of kidney disease. Lead content of blood and deciduous teeth was determined in 22 children aged 5-14 years at different stages of chronic renal failure (CRF). In addition, individual lead exposure was estimated from histories. The results were compared with a control group of 20 siblings or neighbours of patients living in the same environment (C1), and to a group of children known to be free of excessive lead exposure (C2). The mean blood lead concentration of patients was normal (mean 2.9 micrograms/dl, range 1.1.-10.1). Mean dental lead content was 2.8, 1.7 and 1.4 micrograms/g in CRF, C1 and C2, respectively. It always exceeded that of healthy peers. Increased dental lead content was associated with a high risk of exposure. It is suggested that both an increased lead uptake and renal dysfunction may contribute to the increased lead burden in children with CRF.