In this preliminary report, we showed that proteolytic activity of extracts from 85 cervical samples of patients with normal cervix, low and high-grade squamous intra-epithelial lesions and invasive carcinoma, increased according to the natural history of the cervical cancer when measured with three different substrates. Inhibitor assays for four different catalytic classes of endopeptidases indicated that the predominant catalytic class in extracts of all groups was that of metalloproteinases. Substrate gel electrophoresis revealed that invasive carcinoma extracts had two bands with proteolytic activity (with M(r) of 72 and 52 kDa) which were not present in normal tissue or biopsies with precursor lesions. Immunological and molecular characterization of these bands may provide information relevant to cervical cancer biology and clinical applications.