One of the most important legacies of Sir William Osler was his textbook The Principles and Practice of Medicine. A common criticism of the book when it was first published was its deficiency in the area of therapeutics. In this article, the 1st edition of The Principles and Practice of Medicine is compared with the 11th edition of Harrison's Principles of Internal Medicine. The analysis focuses on the treatment recommendations for 4 conditions that were covered in both books (diabetes mellitus, ischemic heart disease, pneumonia and typhoid fever). Osler's textbook dealt with typhoid fever and pneumonia at greater length, whereas Harrison's placed more emphasis on diabetes mellitus and ischemic heart disease. Notwithstanding Osler's reputation as a therapeutic nihilist, the 2 books devoted equivalent space to treatment (in terms of proportion of total sentences for the conditions). For all conditions except ischemic heart disease, Osler concentrated on general measures and symptomatic care. Throughout Osler's textbook numerous negative comments are made about the medicinal treatment of various conditions. A more accurate statement about Osler's therapeutic approach was that he was a "medicinal nihilist." His demand for proof of efficacy before use of a medication remains relevant.