PURPOSE: To evaluate CT findings of mucinous adenocarcinoma in the gastrointestinal tract. MATERIALS AND METHODS : CT scans of 24 gastric and five colorectal mucinous adenocarcinomas, proven by histology, were retrospectively analysed; the patients consisted of 18 men and 11 women (age range, 27-76; mean, 59). CT findings were analysed, with emphasis on : (a) tumor size and maximal wall thickness ; (b) the presence of a low attenuation area, suggestive of a mucin poll within the tumor ; (c) the presence, shape and location of calcification, and (d) correlation between primary tumor (T) staging and CT findings. RESULTS: The mean tumorsize of gastric mucinous adenocarcinoma was 8.2cm (range, 1.4 - 17cm) and the mean maximal wall thickness was2.3cm (range, 1-4.5cm). Low attenuation areas on enhanced CT were seen in 12 cases (50%). Mottled, punctate, diffuse calcifications were demonstrated in nine cases(38%), and were located in low attenuation areas in eight cases. The T staging could be determined in 22 cases. Of there, low attenuation areas were demonstrated in tencases and calcification in seven. Of those ten cases with low atteuation area T staging was T2 in two cases, T3 intwo, and T4 in six. Of the cases showing calcification, T staging was T3 in one case and T4 in six. The mean sizeof colorectal mucinous adenocarcinoma was 6cm(range, 3-13cm) and the mean maximal wall thickness was 3.6cm (range,1.5-7cm). Low attenuation area were seen in three cases. Mottled calcification within the low sttenuation was detected in one case. The T staging of three cases which showed a low attenuation area was T3 in tow cases and T4in one case. One case with calcification was T3 stage. CONCLUSION: The CT finding of mucinous adenocarcinoma inthe gastrointestinal tract was a relatively thick-walled mass containing an area of low attenuation or calcification. Although calcification is believed to be a pathognomonic finding for the specific diagnosis of mucinous adenocarcinoma, a low attenuation area may be an important CT finding because it can be detected at lower T staging and more frequently.