Data from 357 conscious stroke patients taking part in an acute intervention trial and assessed within 48 hours of the onset of symptoms, were used to investigate the prevalence and natural history of swallowing problems. Nearly 30% of patients with single-hemisphere strokes were initially found to have difficulty swallowing a mouthful of water, but in most of those who survived, the deficit had resolved by the end of the first week. Strong correlations were found between dysphagia and speech impairment (comprehension and expression) and with facial weakness, but there was no association with the side of the stroke. After controlling for other markers of overall stroke severity such as conscious level, urinary continence, white blood cell count and strength in the affected limbs, swallowing impairment still showed a significant inverse correlation with functional ability at 1 and 6 months. These results indicate that, even if dysphagia itself is not responsible for much excess mortality in acute stroke, it might still lead to complications which hamper functional recovery.Dysphagia is a common and serious problem after strokes involving both cerebral hemispheres or the brainstem. Because of the bilateral upper motor neuron innervation ofmost ofthe lower cranial nerves involved in swallowing, many textbooks state that the mechanism of deglutition is not significantly affected by damage to a single cerebral hemisphere. Recently, however, it has been pointed out that unilateral hemisphere strokes do affect lower cranial nerve function in general' and swallowing in particular.2-5Clearly, swallowing problems could have serious consequences, with dehydration leading to haemocon- centration, impaired cerebral perfusion and renal failure, and aspiration leading to pneumonia. Data obtained from observations on 357 conscious stroke victims taking part in a trial of beta blockers in acute stroke (the "BEST" Study67) were used to investigate this possibility and to give more detailed information on the natural history of dysphagia after stroke. The results are presented here and the relationships be- tween swallowing problems and other neurological deficits are explored.