BACKGROUND: Idiopathic gastroparesis is a syndrome characterised by severely delayed gastric emptying of solids without an obvious underlying organic cause. Although delayed gastric emptying is traditionally considered the mechanism underlying the symptoms in these patients, poor correlations with symptom severity have been reported. AIMS: To investigate proximal stomach function and to study the correlation of delayed gastric emptying and proximal stomach dysfunction with symptom pattern and severity in idiopathic gastroparesis. METHODS: 58 consecutive patients (19 men, mean (standard deviation) age 41 (2) years) with severely delayed solid gastric emptying (gastric half-emptying time (t(1/2))>109 min) without an organic cause were recruited. They filled out a symptom-severity questionnaire and underwent a gastric barostat study for assessment of gastric sensitivity and accommodation. Correlation of these mechanisms with symptom pattern and overall symptom severity (sum of individual symptoms) was analysed. RESULTS: At two different cut-off levels for gastric emptying (upper limit of normal t(1/2) up to 1.5 and 2 times), no significant change in symptom pattern occurred. 25 (43%) patients had impaired accommodation, and this was associated with higher prevalence of early satiety (p<0.005) and weight loss (p = 0.009). 17 (29%) patients had hypersensitivity to gastric distension, and this was associated with higher prevalences of epigastric pain (p = 0.005), early satiety (p = 0.04) and weight loss (p<0.005). Overall symptom severity was not correlated with gastric emptying or accommodation, but only with sensitivity to gastric distension (R = -0.3898, p = 0.003) and body weight (R = -0.4233, p = 0.001). CONCLUSIONS: In patients with idiopathic gastroparesis, the symptom pattern is determined by proximal stomach dysfunction rather than by the severity of delayed emptying.