the purpose of this study was to establish the prevalence of hematuria in a group of otherwise healthy male runners aged 23 to 54 years (n = 10), and to compare the occurrence of hematuria under four different exercise conditions. the four exercise protocols chosen for the study were: a 60 minute treadmill run (run) at 90% of anaerobic threshold (at), a 60 minute cycle (bike) ergometer ride at 90% of at, three 400 meter sprints (sprint) at maximum effort, each followed by a four minute rest consisting of light walking, and three 60 second wingate cycle ergometery (wingate) at maximum effort, each followed by a four minute rest consisting of light cycling. the study employed a 3 by 4 (time by protocol) within-subjects design. the dependent variables were measured before, four minutes post and one hour post exercise, and included; hematuria, proteinuria, urinary ph, serum haptoglobin (hp), serum creatine kinase (cpk), plasma lactate (pla), and hemoglobin (hb). it was hoped that by observing the occurrence of hematuria under the various conditions, and by cross-examining the dependent variables, further understanding into the mechanisms of hematuria would be gained. repeated 400 meter sprinting at maximal effort was found to significantly increase both hematuria and proteinuria (p < .01). in addition, post exercise hematuria for the sprint protocol was significantly different than both the bike (p < .01) and run (p < .01) protocols. significant correlations were observed between both hematuria (p < .01) and proteinuria (p < .001), with plasma lactate (pla) and with urinary ph (p < .001). due to the significant increase in hematuria and proteinuria following the sprint protocol it was concluded that intensity related changes in renal ftinction were the responsible mechanisms.