AIMS: To investigate the expression of matrix metalloproteinase (MMP)-2, MMP-9, and tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in non-melanoma skin cancer (NMSC) and to compare their expression between different tumour types and with clinicopathological factors. METHODS AND RESULTS: A study of 11 normal skin, 29 Bowen's disease (BD), 40 squamous cell carcinoma (SCC) and 38 basal cell carcinoma (BCC) samples for MMP-2, MMP-9, TIMP-1 and TIMP-2 expression was carried out using immunohistochemistry and in situ hybridization. The expression of all metalloproteinases was greater in tumours than in normal skin. MMP-2 and MMP-9 expression was more extensive in the stroma of SCC than of BCC or BD. TIMP-1 expression was greater in the stroma of BCC than of SCC or BD and TIMP-2 expression was greater in the stroma of SCC than of BD. There was a correlation between increased metalloproteinase expression and depth of lesion (MMP-2 and TIMP-2), inflammation (MMP-2, MMP-9, TIMP-1 and TIMP-2) and microvessel density (MMP-2, MMP-9 and TIMP-2). CONCLUSIONS: MMP-2, MMP-9, TIMP-1 and TIMP-2 play an important role in the pathogenesis of non-melanoma skin cancer, but differ significantly in their expression levels between the tumour types examined. The immunoexpression of these proteins may be useful indicators of cutaneous cancer invasion and progression.