To study the variations of l ipid peroxidation products and copper, zinc-superoxide dismutase(CuZn-SOD) in pathological scars (hypertrophic scars and keloids). Methods The specimens were gained from patients of voluntary contributions from May 2005 to August 2005. The tissues of hypertrophic scar (10 cases, aged 16-35 years, the mean course of disease was 2.2 years), keloid (10 cases, aged 17-32 years, the mean course of disease was 8 months) and normal skin (8 cases, aged 16-34 years) were obtained. The content of malonaldehyde (MDA)and CuZn-SOD activity were detected by spectrophotometric method. The expression of CuZn-SOD was evaluated by immunohistochemistry technique. Results The contents of MDA and CuZn-SOD activity were significantly higher in hypertrophic scars[MDA (1.139 0 ± 0.106 7)nmoL/mg prot, CuZn-SOD (31.65 ± 2.21)U/mg prot, (P lt; 0.05)]and keloids[MDA (1.190 0 ± 0.074 8)nmoL/ mg prot, CuZn-SOD (34.36 ± 5.01)U/mg prot (P lt; 0.05)] than those of normal skin tissues [MDA (0.821 3 ± 0.086 4)nmoL/mg prot, CuZn-SOD (20.60 ± 5.56)U/mg prot]. Immunohistochemical studies indicated that the brown particles were CuZn-SOD positive signals, which mainly located cytoplasm in normal skin tissues, hypertrophic scars as well as keloids epidermal keratinocytes and dermal fibroblasts. CuZn-SOD expression evaluation in hypertrophic scars (4.14 ± 0.90, P lt; 0.05) and keloids epidermal keratinocytes (4.43 ± 0.79, P lt; 0.05) markedly increased when compared with normal skin tissues (2.20 ± 0.45). The expression of CuZn-SODin hypertrophic scars (4.00 ± 0.82, P lt; 0.05) and keloids dermal fibroblasts (4.43 ± 0.53, P lt; 0.05) were significantly higher than that of normal skin tissues (1.60 ± 0.89). There were no differences in the content of MDA, CuZn-SOD activity and expression evaluation between hypertrophic scars and keloids (P gt; 0.05). Conclusion In pathological scars, the contents of MDA and CuZn-SOD activity increase and the expressions of CuZn-SOD are enlarged.