The relevance of DNA-index, alone and in combination with other parameters, was assessed for patients with squamous cell carcinomas of the uterine cervix by using the method of flow cytometry (FCM). Tumours with a diploid or a tetraploid DNA-content appeared to be associated with a less favourable prognosis than was observed in the group with non-diploid/non-tetraploid tumours. DNA-index in combination with either the age of patients or the histological grade of tumours, enabled the separation of prognostically different subgroups. Particularly, the combination of an age under 51 years with a DNA-index of 1 or 2 appeared to define a group with a low survival rate. Furthermore, within the group of well and moderately differentiated tumours, it was possible to identify prognostically different subgroups by combining this parameter with DNA-index, i.e. a non-diploid/non-tetraploid DNA-content of these tumours was associated with a more favourable prognosis. From this study it is concluded that FCM clearly contributes to the recognition of subgroups of patients with different prognosis.