The nuclear DNA of human breast carcinoma cells was studied by image analysis using archival paraffin-blocked tissues from two groups of patients with breast cancers. One group had survived greater than 10 years (N = 20) and the other less than 3 years (N = 26) after the initial diagnosis. Cellular preparations were made from pepsin-digested deparaffinated sections. The nuclear DNA was stained with Feulgen stain and measured by a computerized image analysis system. The data show that in addition to nodal status the pattern of DNA histograms obtained from image analysis can provide powerful prognostic information in breast carcinoma. The prognostic value of DNA histogram patterns may be independent of nodal status.