1. The effects of meal temperature and volume on the emptying of liquid meals have been studied in eight normal volunteers. Four drinks were investigated: (i) 200 ml, 12 degrees C, (ii) 200 ml, 37 degrees C, (iii) 500 ml, 12 degrees C, (iv) 500 ml, 37 degrees C. Gastric emptying was measured by real-time ultrasound. 2. After an initial rapid phase of emptying, measured by the volume retained in the stomach at 5 min, emptying was mono-exponential and measured as a half-life. 3. The 5 min gastric volume was significantly reduced by giving a cold drink of 500 ml (12 degrees C: 250 +/- 33.1 ml. 37 degrees C: 307 +/- 25.8 ml, P less than 0.05). Temperature had no significant effect on the subsequent half-life of emptying. 4. The half-life was longer for meals of larger volume; at 37 degrees C this was statistically significant: 200 ml: t 1/2 7.6 +/- 2.1 min; 500 ml: t 1/2 15.3 +/- 2.8 min; P less than 0.01. 5. There was a significant positive correlation between the 5 min volume and the subsequent half-life of emptying for all meals except 200 ml at 12 degrees C, suggesting that resting gastric muscle tone affects both phases of gastric emptying. 6. Significant correlations within subjects for 5 min volume measurements for meals of different volume and temperature and half-lives of meals at 37 degrees C suggests that individuals have their own characteristics of gastric emptying for liquid meals.