Summary: This study investigated the contents and distribution of collagen Ⅴ (Col Ⅴ) in skin lesions of the patients with systemic sclerosis (SSc) and its roles in the pathogenesis. The contents and distribution for al chain of collagen type Ⅰ,Ⅲ and [α1 (Ⅰ), α1 (Ⅲ) and α1 (Ⅴ)] in skin lesions of 36 patients with SSc (9 cases of mild fibrosis, 14 moderate, and 13 severe) were detected by using immunohistochemical SP method. Six cases of normal skin tissues served as controls. The results showed that there was diffuse distribution for three kinds of collagens in dennis. The deep staining α1 (Ⅰ) and α1 (Ⅲ) masses or bands were seen in reticular layer, while α1 (Ⅴ) was distributed more homogeneously. From control to weak, moderate and severe fibrosis stages, α1(Ⅰ), α1 (Ⅲ) and α1 (Ⅴ) showed a gradually increased trend in skin lesions (P<0.05). α1(Ⅴ) was obviously elevated in skin lesions at early stage and persisted in whole fibrotic process and risen in greater contents, while α1 (1) and α1(Ⅲ) were to go higher late and were apparently elevated at moderate and late stages. Compared with α1(Ⅰ), α1(Ⅴ) took leading increase at early stage in skin lesions (P<0.01), and had more elevated contents than α1 (Ⅲ) at moderate and late stages. The fibrotic changes in dermal reticular layer occurred earlier than those in papillary layer, and the abnormalities of α1 (Ⅴ)/ α1(Ⅰ) ratio appeared before α1 (Ⅲ)/α1 (Ⅰ) ratio. It was concluded that a lot of α1(Ⅴ) began to deposit in greater contents prior to α1 (Ⅰ) and α1(Ⅲ) at early stage in SSc and persisted in whole fibrotic process. The changes of α1(Ⅴ) contents in reticular layer occurred earlier than those in papillary layer, and it suggested that the fibrosis in reticular layer appeared earlier.