One hundred and seventy patients with multiple sclerosis and bladder dysfunction were evaluated. Emphasis was placed on the relationship between their neurological features and urinary symptoms. The severity of the urinary symptoms was related to the degree of pyramidal impairment in the lower limbs so that both problems are thought to reflect the extent of spinal involvement. No other neurological features correlated with bladder dysfunction. Detrusor hyperreflexia was the commonest finding on cystometry and no patient had areflexia. More than half of the patients had a significantly raised post-micturition residual volume but symptoms were largely unreliable in predicting poor bladder emptying. In this series only two patients had evidence of upper tract disease: both men with severe, longstanding neurological disease who had indwelling catheters. Detrusor hyperreflexia can be anticipated in patients with MS who have irritative urinary symptoms and pyramidal signs in their lower limbs. After measurement of the residual volume appropriate treatment can be instituted.