Ten male Bedouin from the Negev have been compared with the same, or for one test a much larger, number of Jewish male students of a similar age. Their heights, weights and serum chemistry were similar although the Bedouin were somewhat thinner. The response of the sweat glands to pilocarpine was smaller in the Bedouin than in the controls. Their forearm bloodflows at rest were greater. Their production of sweat in response to a rise of deep body temperature was the same and so was their working capacity and the concentrating power of their kidneys. Physiologically speaking, therefore, Bedouin did not appear to be better adapted to life in the desert than other human ethnic groups.