Wound fluids were collected up to 60 h after abdominal surgery. Immediately after obtaining the wound fluid by Robinson drainage, wound fluid was centrifuged to remove blood cells and inflammatory cells. The concentration of total protein as well as of thymosin beta(4) was determined in the cell-free supernatant solution. Total protein concentration decreased from about 50 g/L to 30 g/L within 60 h after surgery. After surgery we observed a concentration of up to 20 mg thymosin beta(4) per liter decreasing to about 1 mg/L with time. Neither thymosin beta(10) nor oxidized thymosin beta(4) was detected in human wound fluid.