The level of tissue kallikrein in serum and urine, and of an erythrocyte kallikrein-like enzyme, were compared in 10 subjects without hypertension and in 10 patients with hypertension with normal renin levels. Each group consisted of five men and five women. All subjects were observed at a general clinical research center for consecutive 5- to 6-day periods of daily dietary sodium intake of 109, 9, and 259 mEq. Tissue kallikrein levels in serum and urine and levels of the erythrocyte kallikrein-like enzyme were measured with specific radioimmunoassays or with an activity assay, respectively. Mean active and total urinary kallikrein excretion rates were higher in women than in men (both with and without hypertension) when they were given all diets (p less than 0.05 to 0.025), and these rates varied inversely with sodium intake. The serum immunoreactive tissue kallikrein level was higher in men than in women when they were given all diets (p less than 0.05 to 0.001), but there was no difference between subjects with and without hypertension. There were no consistent changes in levels with altered sodium intake. Erythrocyte kallikrein-like esterase activity was greater in women without hypertension than in men without hypertension (p less than 0.05 to 0.001) when receiving the 9 and 109 mEq sodium diets, but values were similar in all groups receiving the 259 mEq sodium diet.(ABSTRACT TRUNCATED AT 250 WORDS)