The DNA content of Feulgen-stained monolayer imprint preparations from 30 fresh frozen soft tissue and bone sarcomas was analyzed using image cytometry. DNA aneuploidy showed a significant association with increasing tumor grade. Of the grade III tumors, 83.3% (15 of 18) were aneuploid; of the grade I and II sarcomas, 33.3% (4 of 12) were aneuploid (P less than 0.00861). The proliferation index (PI) was determined by the percentage of tumor nuclear area staining with the monoclonal antibody Ki-67. The PI was significantly associated with ploidy and tumor grade. Ki-67 PI was elevated (greater than 2.0%) in 73.7% (14 of 19) of the aneuploid tumors, compared with 30% (3 of 10) of the euploid tumors (P less than 0.04597). Ki-67 PI was greater than 2.0% in 77.8% (14 of 18) of the grade III tumors, compared with 27.2% (3 of 11) of the grade I and II tumors (P less than 0.01773). These findings suggest that DNA ploidy and Ki-67 PI as determined by image analysis may be a useful supplement to tumor grading. The literature examining previous studies of sarcoma DNA ploidy is reviewed.