The clinicopathological and DNA flow cytometric data of 33 patients with stromal tumours of the gastrointestinal tract (STGIT) were analysed to select pathological features of prognostic value. Tumours had been previously classified as benign (21 cases) or malignant (12 cases). Data relating to poor prognosis statistically were local invasion, pathological grade, size greater than 10 cm, mitotic index (MI) and necrosis. Pathological grade was related to local invasion. Aneuploidy did not correlate with poor survival although a common trend was detected between both. DNA content may help to predict prognosis of STGIT, but its real value has not yet been clearly established. Currently, stage (invasion), size, MI and pathological grade remain the most useful prognostic factors.