Only few data are available on intestinal calcium absorption from foodstuffs and composite meals in humans. The aim of the study was to compare intraindividually the calcium absorption from milk and from a breakfast with that from a pharmaceutical calcium preparation of equal calcium content. In 8 healthy volunteers between 44 and 58 years of age, the intestinal calcium absorption was measured in randomized order applying the double isotope technique from: (1) 500 ml of fresh milk (equivalent to 620 mg Ca), (2) a test meal composed of 250 g curd, 150 g yoghurt, 3 slices of pineapple, 2 breakfast rolls, 2 cups of coffee, 10 g of coffee cream, 20 g butter, 50 g jam and 20 g honey (equivalent to 580 mg Ca), and (3) a lactogluconate effervescent tablet (equivalent to 500 mg Ca). All test doses were given on an empty stomach and labelled with 20 mg44Ca. Simultaneously, 5 mg42Ca in a sterile isotonic solution were injected intravenously. The mean values of the absorbed fractions are 24.0% ± 5.4% (mean ± SD), 17.9% ± 7.1%, and 28.7% ± 9.1% for the milk, for the meal and for the tablet respectively. The data show that less calcium ist absorbed from foodstuffs as compared to a preparation of optimal bioavailability. But in this study only the difference between absorption from the milk and from the meal was statistically significant. Therefore, it is possible to obtain a sufficient calcium supply of the human body also by properly selected foodstuffs.