Matrix metalloproteinases are involved in tumor invasion and metastasis in many types of human carcinomas, in leukocyte infiltration and inflammatory reactions. Three metalloproteinases with gelatinolytic activity were isolated from the urine of patients with untreated high grade bladder cancer or with functioning renal grafts (control). Urinary proteins were fractionated after concentration by continuous-elution SDS-polyacrylamide gel electrophoresis. Collected fractions were analyzed by gelatin zymography and Western blotting. The one-step purification process isolated the gelatinase species from crude urine samples: (1) a 72 kDa progelatinase A (MMP-2) and its actived 68 kDa form; (2) a 92 kDa progelatinase B (MMP-9); (3) a higher molecular weight (HMW) complex (115 kDa) which was identified as progelatinase B associated with lipocalin, NGAL. A similar marker profile was observed in bladder cancer tissues. The current study demonstrated the efficiency of continuous elution electrophoresis. It offered two main advantages: (1) the separation of latent from active gelatinase isoforms with no interference from the TIMPs and (2) the identification and isolation in a single step of large amounts of urine gelatinase species with both high recovery and significant specific activities. Continuous-elution electrophoresis can be used for correlation with clinical events of bladder cancer diagnosis and prognosis.