Wound fluid collected from chronic wounds may be used as a simple gauge of the processes taking place in the tissue. There is lack of information on the optimal conditions for wound fluid procurement. We have studied possible diurnal variations and duration of wound fluid accumulation using retentive hydrophobic foam on the levels of prototypic cytokines [interleukin (IL)-1a, IL-1ß], a chemokine (IL-8) and proteinases [matrix metalloproteinase (MMP)-9] in 23 chronic venous leg ulcer patients. Bioactivity of 1 and 24 h wound fluids, and serum was also compared. There were no significant temporal changes in the levels of the above-mentioned four proteins, when comparing three consecutive 8-h intervals starting from 0800 that in turn did not differ significantly with the 24-h collection levels. IL-1a, IL-1ß and IL-8 levels were higher (p