Over a 12-year period (1957–1969) at University College Hospital, Ibadan, 9600 patients suffering from neurological diseases have been seen out of 220,000 patients investigated in the wards and specialty clinics of the hospital which is situated in the largest negro city in the World. The incidence of neurological diseases in the hospital population is 4.2%. Infections of the nervous system constitute the commonest neurological problem; they account for 43% of all neurological diseases and the incidence in the hospital population is 19 per thousand. Tetanus and the meningitides account for 80% of infectious diseases of the nervous system, tetanus being the commonest neurological disease. Neurosyphilis is uncommon in Southern Nigerians. The incidence of vascular disease of the nervous system is 2.6 per thousand. Non-embolic ischaemic cerebrovascular disease is the commonest disorder. Epilepsy and other paroxysmal disorders have an incidence of 3.2 per thousand. For epilepsy aetiological factors are idiopathic (70%), infections (9.4%), vascular lesions (6.5%), trauma (6.2%), neoplasms (3.6%), metabolic causes (1.5%) and birth injury (1.3%). Migraine is not uncommon, and is found mainly in females. Ménière's syndrome is rare. Congenital malformations (spina bifida occulta, spina bifida manifesta, Arnold-Chiari malformation, congenital hydrocephalus) have an incidence of 2.1 per thousand in the hospital population. Cerebral palsy is common (2 per thousand). The incidence of motor neurone disease is 0.35 per thousand; the mean age of the patients is considerably lower than in Caucasians and it does not carry the same inexorably bad prognosis. The heredofamilial spino-cerebellar degenerations are very rare. More than 80 primary intracranial tumours have been seen. All 14 intracranial tuberculomas were supratentorial. Chorioncarcinoma is the commonest tumour that metastasizes to the brain. Extrapyramidal syndromes (the commonest is Parkinson's disease) occur in 0.7 per thousand of the hospital population. Hepatolenticular degeneration was seen in 6 Nigerians, but there was no evidence of abnormal copper transport. Multiple sclerosis is unknown in Nigerians, but neuromyelitis optica (0.4 per thousand) and acute bilateral retrobulbar neuritis are not uncommon. Tropical ataxic neuropathy constitutes the commonest spinal cord syndrome (1.8 per thousand of population). Fifty-four (0.24 per thousand) patients with intraspinal canal neoplasms were seen, most of which were epidural tumours. Spondylotic myelopathy is not rare, but sciatica from intervertebral disc disease is uncommon. Peripheral neuropathy has an incidence of 2.1 per thousand in the hospital population, and various aetiological factors were encountered, the commonest being malnutrition. Bell's palsy is common (0.4 per thousand). Trigeminal neuralgia is uncommon. Pyomyositis, a suppurative inflammatory disease, is the commonest disease of muscle in Nigerians (1 per thousand). The muscular dystrophies (0.13 per thousand) and polymyositis (0.17 per thousand) were also seen. The significance of some of these findings in the light of the pattern of neurological illness described elsewhere and from other parts of Africa is discussed.