Intermediate and high grade subtypes of non-Hodgkin's large cell (LCL) and immunoblastic lymphomas exhibit considerable variability, and histologic morphology alone may not adequately characterize those features important for prognosis. The relationship between nuclear morphology and survival was assessed in a series of 50 cases of large cell lymphomas in which ploidy, proliferation, and nuclear area (NA) were measured. Ploidy was calculated by both DNA index (DI) and DNA histogram type (DHT). Proliferation was calculated from the proportion of S phase (SPF) cells present in the DHT. These four parameters were measured using image cytometry of Feulgen-stained nuclei from fine-needle aspirations. To characterize the relationship with survival, these parameters were associated with the clinical follow-up of the patients. The results show that of the 50 LCL cases, only 5 were clearly aneuploid, whereas the remaining 45 were either diploid (29 cases), tetraploid/hypotetraploid (13 cases), or weakly aneuploid (hyperdiploid, 3 cases). Of the 34 patients who died from their disease, both smaller NA and DI correlated with longer survival in an equivalent fashion; neither conferred greater sensitivity when combined with the other. The SPF did not correlate with survival. In LCL, aneuploidy seems to be a relatively uncommon event, but when present ploidy measurement appears useful to define prognosis.