The blood pressure behavior during and after ergometric exercise was investigated in 552 males in order to clarify if this standardized procedure is suitable for differentiating between normotensive subjects and hypertensive patients. Patients suffering from mild hypertension showed significantly (p < 0.001) higher blood pressures (213 ± 22/116 ± 11 mm Hg) at 100 W and after loading than age-matched normotensives (188 ± 14/92 ± 9 mm Hg) but significantly (p < 0.001) lower values than hypertensives with stable hypertension (225 ± 22/126 ± 11 mm Hg). Moreover, the systolic pressure response to ergometric work was significantly (p < 0.05 – p < 0.01) influenced by age. Using the normal upper limits for blood pressure during and after ergometry the ergometric procedure revealed that 50% of the patients with borderline hypertension at rest could be classified as hypertensives. Their blood pressure response at 100 W (216 ± 21/113 ± 8 mm Hg) did not significantly differ from the patients with mild hypertension. In contrast, in the 50% who reacted negatively to ergometric testing, the systolic blood pressure response at 100 W (204 ± 18 mm Hg) was significantly (p < 0.01) lower than that of those who demonstrated a positive reaction, revealing exactly the same diastolic blood pressure value of 92 mm Hg as the normotensives. The present study strongly suggests that the assessment of blood pressure during ergometric testing is quite useful in distinguishing between normotensive and hypertensive patients and in making estimates of blood pressure response to daily stress more accurate.