Slightly increased urinary albumin excretion rates (UAE) have been reported in patients with various types of human cancer. We measured UAE in 24 h urine samples from 48 untreated patients with non-Hodgkin's lymphoma at diagnosis. In patients with a pretreatment UAE >/=20 microgram/min, post-treatment value of UAE was determined following completion of the last treatment. The median UAE was 15.0 microgram/min and the prevalence of microalbuminuria (UAE >/=20 microgram/min) was 39.6%. Increased UAE was significantly associated with Ann Arbor stage, performance status, serum lactate dehydrogenase (LDH) level, and the International Prognostic Index (IPI). The median posttreatment value of UAE was significantly lower than the pretreatment value (P < 0.0001). Our data suggest a clinical and prognostic significance of UAE in patients with non-Hodgkin's lymphoma.