A single-film intravenous pyelogram was performed on 87 children with acute lymphoblastic leukemia at presentation. The kidney size was measured and a standard deviation score based on patient height was calculated. There was a tendency of renal enlargement, with 21 patients (24%) having scores of over 1 SD and 6 (7%) over 2 SD. A trend of shorter duration of first remission with increasing renal size was shown to be statistically significant (P = 0.036). This trend was not quite statistically significant (P = 0.087) whenthe analysis was confined to 54 "better-risk" patients (WBC less than 20 X 10(9)/liter and no mediastinal mass), and was much weaker and not significant in 33 "poor-risk" patients (P = 0.62).