We studied the DNA content, DNA index and cell cycle parameters that are reliable markers for assessing the proliferative activity and aggressiveness of malignancies. Cytometric DNA analysis was performed on formalin-fixed paraffin embedded sections from 36 Iraqi patients with oral squamous cell carcinoma. The results showed that 20 of 36 cases (55.5%) were diploid, while 15 cases (41.7%) were aneuploid. Significantly higher S-phase fractions and higher DNA indices characterized aneuploid tumours. Nuclear DNA analysis as part of the evaluation of oral squamous cell carcinoma will influence the selection of appropriate treatment strategies.