Bodyweight has been shown to influence anidulafungin exposure, but data from obese patients are lacking. We determined anidulafungin pharmacokinetics (100-mg single dose) in eight morbidly obese subjects (body mass index >40 kg/m(2)). Anidulafungin exposure was on average 32.5 % lower compared with the general patient population, suggesting dose increases may be required in this population.