Vesicovaginal fistula was a catastrophic complication of childbirth among 19th century American women. The first consistently successful operation for this condition was developed by Dr J Marion Sims, an Alabama surgeon who carried out a series of experimental operations on black slave women between 1845 and 1849. Numerous modern authors have attacked Sims's medical ethics, arguing that he manipulated the institution of slavery to perform ethically unacceptable human experiments on powerless, unconsenting women. This article reviews these allegations using primary historical source material and concludes that the charges that have been made against Sims are largely without merit. Sims's modern critics have discounted the enormous suffering experienced by fistula victims, have ignored the controversies that surrounded the introduction of anaesthesia into surgical practice in the middle of the 19th century, and have consistently misrepresented the historical record in their attacks on Sims. Although enslaved African American women certainly represented a "vulnerable population" in the 19th century American South, the evidence suggests that Sims's original patients were willing participants in his surgical attempts to cure their affliction-a condition for which no other viable therapy existed at that time.