Proliferating cell nuclear antigen (PCNA) is a DNA replication protein maximally elevated in late G1 and S phases of the cell cycle. By using monoclonal antibodies, the expression of PCNA can be quantified and the rate of tumour cell proliferation estimated. The degree of DNA aberration in a tumour cell population reflects its genetic instability and has been implicated as a prognostic factor in an increasing number of solid tumours. The nuclear DNA content can be assessed by densitometric image cytometry DNA analysis. Both PCNA and DNA analysis can be performed on histological sections from paraffin embedded biopsies. In search of efficient and reproducible methods to identify early glottic cancers with increased risk for recurrence after radiotherapy, the PCNA expression as well as the DNA content of the diagnostic biopsies from 28 T1N0M0 glottic cancers were assessed. The group of tumours which recurred locally after radiotherapy displayed lower PCNA expression and higher DNA aberration than the group of tumours which were cured. Moreover, a combination of both parameters improved the possibility to discriminate the two groups. For T1 glottic cancer displaying high grade of genetic instability or low grade of proliferation, treatment regimes other than radiotherapy and closer follow-ups could be considered.