Cardiovascular responses to sustained isometric hand grip were investigated in 18 healthy adult males, six of whom were undernourished labourers with a low body mass index. The undernourished subjects had the lowest basal systolic blood pressure and demonstrated the smallest rises in systolic and mean arterial pressure following sustained isometric hand grip for two minutes at 50% maximum voluntary contraction. The results indicate a reduced functional response in the undernourished possibly due to reduced activity of sympathetic nervous system function.