1. In male Wistar rats urinary kallikrein excretion was positively correlated with urinary flow and glomerular filtration rate (GFR).
2. Osmotic diuresis produced by a 30% (w/v) glucose solution increased urinary kallikrein, and a positive correlation between this variable and urine flow was observed. No correlation was observed with GFR.
3. The mechanism of urinary kallikrein excretion is interpreted as a wash-out effect of renal kallikrein.