Epigastric impedance recording was used to measure gastric half-emptying time (t1/2) of orange squash in 45 healthy infants and children. The relationship between age, body size, and composition and the impedance increase after gastric filling was investigated, together with the effects on half-emptying time of adding fat, increasing viscosity, and increasing osmolality in the test meal. The mean t1/2 for orange squash was 13.5 min. The increase in impedence per unit volume ingested showed a significant inverse relationship with age (r = -0.62, p < 0.001), and with various anthropometric variables (r ranged from -0.48 to -0.80, p < 0.01). No relationship was observed between t1/2 and age, sex, body size, or composition. Addition of 1.25% triglyceride or a 600-fold increase in viscosity of the test meal were both accompanied by a significant lengthening of t1/2 (p = 0.005 and p < 0.001, respectively), but t1/2 did not alter with a fourfold increase in test meal osmolality. The test was well tolerated by all subjects, but its usefulness is limited by susceptibility to movement artefact, and also the necessity to use simple, liquid test meals.