BACKGROUND: Recent observations in limited numbers of patients suggest a potential benefit of intrapyloric injection of botulinum toxin in the treatment of gastroparesis. AIM: To characterize the effect of botulinum toxin on solid and liquid gastric emptying and on meal-related symptoms. METHODS: In 20 gastroparesis patients (17 women, mean age 37 +/- 3 years, three diabetic and 17 idiopathic), gastric emptying for solids and liquids was measured before and one month after intrapyloric botulinum toxin 4 x 25 units. Before the meal and at 15-min intervals up to 240 min postprandially, the patient graded the intensity of six gastroparesis symptoms, and a meal-related severity score was obtained by adding all intensities. Data (mean +/- S.E.M.) were compared using paired Student's t-test. RESULTS: Treatment with botulinum toxin significantly enhanced solid (t(1/2) 132 +/- 16 vs. 204 +/- 35 min, P < 0.05) but not liquid (92 +/- 10 vs. 104 +/- 11 min, N.S.) emptying. This was accompanied by a significant decrease in cumulative meal-related symptom score (73.5 +/- 16.3 vs. 103 +/- 17.1 baseline, P = 0.01) as well as individual severity scores for postprandial fullness, bloating, nausea and belching (all P < 0.001, two-way anova). CONCLUSIONS: Botulinum toxin improves solid but not liquid gastric emptying in gastroparesis, and this is accompanied by significant improvement of several meal-related symptoms.