While medical historians have paid ample attention to the introduction of antibiotics and their impact on hospital-based practice during and after the Second World War, the multiple issues surrounding their use in Scottish hospitals are sorely lacking in current discussions. Drawing on an extensive yet underused range of materials including patient treatment records, oral histories and medical correspondence, this paper explores the introduction of penicillin for civilian treatment at the Royal Infirmary of Edinburgh during the closing stages of the War. It highlights the success of the drug in clinical treatment as well as its shortcomings, offering an alternative view of its initial impact on surgical practice.