This research studies the effects of air conditioning on blood pressure and the heart rate. It is based on studying the blood pressure and pulse of 32 young healthy Nigerian volunteers after they had been in an air-conditioned room from between 60 and 90 minutes. The same measurements were made under the same conditions with the air-conditioning switched off. The mean systolic blood pressure (SBP) was 115.3 +/- 11.5 mm Hg with air conditioning (AC) and 108.5 +/- 10.1 mm Hg without air conditioning. This difference was statistically significant. Similarly, diastolic blood pressure (DBP) was higher with AC, 69.4 +/- 8.9 mmHg, than without AC, 66.5 +/- 9.1 mmHg, while mean blood pressure was also higher in AC, 84.9 +/- 9.1 mmHg, than without, 79.9 +/- 7.7 mmHg. There was no significant change in pulse rate. These differences in the BP of normal young subjects were probably not clinically significant but the results suggest that the study of the effect of AC on BP and pulse in older or hypertensive subjects is necessary.