In the first half of the twentieth century, hormones took pride of place as life's master molecules and the endocrinologist took precedence over the geneticist as the scientist offering the means to control life. But, as with molecular genetics and biotechnology today, the status of endocrinology was not based solely on contemporary scientific and medical practices. To a high degree it was also reliant on expectations or visions of what endocrinologists would soon be able to do. Inspired by the approach (...) of social studies of techno-scientific expectations, the aim of this article is to explore some of the great expectations connected to the development of endocrinology in the 1930s. The analysis is based on popular books written by the American physician and endocrinologist Louis Berman. The paper argues that Berman thought not only that it was perfectly possible to understand human nature through hormone analysis but that endocrinologists would be able to control, design and ‘improve’ humans by using hormone replacement therapy. Furthermore, in contrast to most of the eugenics of his time, Berman suggested that the whole population of the world should be improved. As a political activist he wanted to contribute to the development of new human beings, ‘ideal normal persons’, thereby reaching an ‘ideal society’. That HRT could involve risks was something that he seems not to have taken into account. (shrink)