BACKGROUND:The acute effects of cigarette smoking on gastric emptying are controversial, whereas its effects on the intragastric distribution of solids and liquids are not established. METHODS:Dual isotope gastric scintigraphy was performed in 15 habitual smokers (studied twice, either sham smoking or actively smoking) and in 15 age- and sex-matched nonsmokers. RESULTS:Acute smoking was associated with an increased prevalence of episodes of retrograde intragastric movement of solids (3 of 15 sham subjects vs. 12 of 15 actively smoking subjects; P < 0.01) and of liquids (0 of 15 vs. 7 of 15; P < 0.01) from distal to proximal stomach. Fundal half-emptying time (T1/2) for liquids was also prolonged by smoking (43 +/- 19 minutes sham vs. 125 +/- 216 minutes active; P < 0.05). Acute smoking delayed solid lag time (13 +/- 6 minutes sham vs. 32 +/- 18 active; P < 0.05) and liquid T1/2 (46 +/- 21 vs. 90 +/- 50 minutes; P < 0.05). In the nonsmokers, such episodes of proximal intragastric redistribution did not occur, and intragastric and overall emptying parameters did not differ significantly from those of habitual sham smokers. CONCLUSIONS:Acute cigarette smoking produces excessive antrofundal redistribution of both solid and liquid contents and delays solid and liquid gastric emptying.