In developed countries, malnutrition is common in patients with chronic renal failure (CRF) and has adverse effects on patient morbidity and mortality. The prevalence of malnutrition before the initiation of dialysis is poorly characterized in CRF patients in developing countries. We studied the prevalence of malnutrition among Nigerians with CRF before commencement of dialysis. Body mass index (BMI) and serum protein levels were measured in 74 dialysis naïve Nigerians with CRF and 48 controls. Patients with nephrotic syndrome, steroid use and failure of organs other than the kidneys were excluded. The mean BMI was significantly lower in the patients compared to the controls (22.4 +/- 14.9 kg/M2 Vs. 25.2 +/- 2.7 kg/M2; p = 0.0001). Low BMI (less than 20 Kg/M2) was present in 16 (21.6%) of the patients compared with one of the controls. The mean serum total protein and albumin were also significantly lower in the patients compared to controls (61.9 +/- 14.4 g/L Vs. 73.8 +/- 6.8 g/L; p < 0.0001, and 31.5 +/- 9.3 g/L Vs. 39.6 +/- 4.4 g/L; p < 0.0001 respectively). Protein malnutrition (serum albumin < 29 g/L) was present in 32 (43.2%) of patients with CRF and one (2.1%) of the control subjects. Malnutrition is common in Nigerian CRF patients before the commencement of dialysis. In these patients, emphasis should be placed on prevention and/or correction of malnutrition because of its documented adverse effects on the outcomes of maintenance dialysis.