Plasma gonadotropins were measured in 126 postmenopausal women (age range 69-90 years) admitted to a geriatric ward. After clinical examination, patients were classified as 'acutely or severely ill' or as 'not ill'. Plasma gonadotropins were compared between both groups. Logistic regression was used to select clinical and/or biochemical parameters which differentiated patients with abnormal, low gonadotropins from patients with high gonadotropin concentrations. Plasma gonadotropins were significantly lower in the 'acutely or severely ill' than in the 'healthy' patient group. By logistic regression, blood sedimentation rate, total protein concentration, and serum thyrotropin concentration were significantly correlated with low gonadotropins. Linear regression analysis showed a significant linear relationship between plasma gonadotropins and age (at least for ages over 80 years), blood sedimentation rate (at values more than 65 mm) and total protein concentration. Marked suppression of plasma gonadotropins was frequently found to occur in acutely ill postmenopausal women, in relation to biochemical parameters of acute illness such as blood sedimentation rate, total protein concentration, and serum thyrotropin. In addition, ageing per se seems characterized by a progressive attenuation of the high postmenopausal gonadotropin levels.