An observational study was undertaken to provide a microstructural analysis of the effects of the selective dopamine D1 receptor agonist, SK&F 38393, on feeding and associated behaviours in the rat. Adult, male non-deprived rats were adapted to eating a meal of sweetened mash in a 30-min period. SK&F 38393 (3.0 and 10 mg/kg, SC) significantly reduced food consumption). It also reduced the frequency of feeding bouts and the local rate of eating, while there was an increase, at 10 mg/kg, in the mean duration of individual feeding episodes. The D1 receptor agonist also reduced the total duration of locomotor activity, but did not affect the total duration of rearing, grooming, sniffing, oral behaviours (other than feeding), or resting. The frequency of bouts of locomotion, rearing, grooming, and sniffing were reduced by SK&F 38393. Consideration of the time-courses for the several responses suggested that SK&F 38393 did not materially affect the form and sequence of behavioural responses in the test, although some changes occurred.