This study was designed to compare by scintigraphy the gastric retention of a new dosage form of sucralfate as gel (Gastrogel) with that of sucralfate suspension in 25 patients with upper gastrointestinal symptoms referred for routine endoscopy. After endoscopy 4 subgroups were defined: macroscopically normal mucosa (n = 7), antral gastritis and/or erosions (n = 6), gastric ulcer (n = 6) and duodenal ulcer (n = 6). Each patient received either sucralfate gel or sucralfate suspension in equivalent doses (5 ml containing 1 g sucralfate). Both formulations were labelled with 111 MBq 99mTc-DTPA before administration. The mean value of t1/2 in the total group was significantly longer when patients were taking sucralfate gel (61.6 min) compared to sucralfate suspension (33.8 min) (P < 0.001). The mean values of t1/2 were significantly longer for sucralfate gel compared to sucralfate suspension also among the subgroups (macroscopically normal P < 0.02, antral gastritis P < 0.05, gastric ulcer P < 0.02 and duodenal ulcer P < 0.05). After 2 and 3 hours, the percentage residual activity in the gastric area was significantly higher following administration of sucralfate gel compared to sucralfate suspension. This study has shown that, compared to sucralfate suspension, sucralfate gel persists longer in the stomach of patients with gastritis and peptic ulcer.