One thousand, two hundred and eighty-five men and 1,080 women being followed in the DHSS Hypertension Care Computing Project answered the questions on sexual activity included in a self-administered questionnaire. In men, both impotence and sexual inactivity were increased in patients receiving hydralazine. No gross excess of these complaints could be determined in patients receiving either beta-adrenoceptor blocking drugs or methyldopa, nor was failure of ejaculation increased with these drugs. The survey could not exclude any deterioration in sexual function occurring uniformly across all treatment groups. However, the rates of complaint were similar in men taking a diuretic alone, a beta-adrenoceptor blocking drug alone and those taking the combination of these two drug groups. In women with hypertension, frequency of sexual intercourse and the achievement of orgasm was not associated with the giving of hydralazine, beta-adrenoceptor blocking drugs or methyldopa.