Human adipsin is recognized to be identical to factor D, which plays an important role in activation of the alternative complement pathway. Since adipsin/factor D is present in high amounts in adipose tissue, liposuction theoretically could result in an increased release of this serine protease into the bloodstream. In the present study, adipsin/factor D was measured in 22 patients undergoing syringe-assisted liposuction using the superwet or tumescent technique. Despite a relatively high mean aspirate volume (2648 ml), only a very modest increase in adipsin/factor D concentration was found during liposuction. All values before, during, and after liposuction were within the range found in healthy blood donors. Furthermore, there was no correlation between adipsin/factor D values and C3 activation products. We conclude that liposuction with the present techniques results in a very modest release of adipsin/factor D that is not associated with increased complement activation.