The pH value of chronic wounds influences directly or indirectly many factors important to wound healing. We measured 247 pH values in 39 patients with chronic wounds of varying origins, detecting values from 5.45 to 8.65. Over a period of 12 months, individual values varied up to 1.73 units. Knowledge of pH values helps insure an adequate chronic wound therapy. For example, many enzymatic wound products have pH values outside the above values. Our results also show that the pH value is a dynamic factor which should be monitored regularly. Our studies offer additional insight into the specific features of chronic wounds and allow a more individualized therapy.