Quantitative 99mTc-dimercaptosuccinic acid (99mTc-DMSA) renal scintigraphy was used to asses ifosfamide-induced changes in renal function in 11 children who received chemotherapy for various malignancies. Serial measurements of absolute 99mTc-DMSA renal uptake, calculated on conjugated views, were performed during and after chemotherapy. Data of 37 studies obtained before and at different cumulative dose levels of ifosfamide were analysed in relation to clinical and biochemical parameters. A highly significant relationship between 99mTc-DMSA uptake and cumulative ifosfamide dose was found (P<0.001). The most frequently observed abnormal pattern on scintigraphic images was decreased kidney uptake together with increased accumulation in bladder. 99mTc-DMSA uptake was more consistent than β2-microglobulin values in urine and more sensitive than quantitative hyperaminoaciduria and tubular resorption of phosphate for the detection of ifosfamide-induced tubular dysfunction. 99mTc-DMSA uptake was decreased in both patients with and patients without clinical toxicity. Persistently reduced 99mTc-DMSA uptake was observed in four patients during follow-up; in one of them, who was asymptomatic after ifosfamide therapy, sudden onset of Fanconi syndrome was observed when he was retreated with carboplatin 1 year later. It is concluded that 99mTc-DMSA renal scintigraphy is a suitable method to assess progressive ifosfamide-induced tubular injury whereas scintigraphic imaging is helpful for interpreting renal uptake changes. The test is able to detect subclinical injury and may potentially predict high risk at retreatment.