Reinhold Mueller has been the one and only historian of medicine in Germany who worked in the field of the Indian history of medicine from the 1920s to the 1960s. He influenced German, American and Indian researchers, but he was nearly forgotten soon after his death. This is the first paper about his life and work to be published. Mueller studied a wide range of topics, the history of Indian gynaecology, of psychiatry, of immunology and of general practice and his subsequent articles were published in the principal contemporary magazines. However, he did not have a perfect understanding of Sanskrit language and writing. Moreover, as he subordinated his research to the premises of National Socialism and of communism, some of his articles have to be seen as part of an Aryan-Germanic race discourse. Yet, these inadequacies and mistakes did not prevent other researchers from maintaining contact with him after 1945. Even when Anglo-American historians of medicine began to study Indian medicine in the 1980s, his publications were re-examined and analysed.