The prognostic value of parameters as determined by DNA flow cytometry, in combination with other parameters, was assessed in 75 patients with ovarian carcinomas (20% in stage I and II). DNA- index of the tumours appeared to predict mainly the degree of differentiation, since the DNA-index only tended to affect prognosis and low grade tumours were mainly diploid. However, with ascites a non-diploid DNA-index was associated with a significantly lower survival in short-term follow-up. Subgroups with a favourable prognosis were defined by an age of patients less than or equal to 40 years, grade 1 tumours, and tumours in stage I or II. Particularly favourable was the combination of a grade 1 tumour, or a tumour in stage I or II, with percentage of cells in G1 greater than 85%. Prognostically poor subgroups were defined by an age greater than 60 years, by grade 2 or 3 tumours and by a clinically advanced stage. The combination of grade 2 or 3, or a clinically advanced stage, with G1-phase fraction less than or equal to 85% identified subgroups with a particularly poor prognosis.