Records of 17 patients who had two or more attacks of pyogenic meningitis were collected from eight centres in the United Kingdom for retrospective analysis. Thirteen patients had intracranial abnormality; of seven with head injury five produced cerebrospinal fluid rhinorrhoea. The first of the 28 attacks seen in these occurred between a few weeks and 12 years of the head injury. Pneumococci were identified in 25 episodes in cerebrospinal fluid. Of six patients without a history of head injury, one had 'spontaneous cerebrospinal fluid rhinorrhoea' and five had pathological changes of the ear. Various organisms were found in the cerebrospinal fluid during the 12 attacks in these five. Four of the 17 patients had primary complement deficiency (C7, C5, C4 and C3b inhibitor); 10 (possibly 11) of 16 attacks in these cases were due to Neisseria meningitidis. Routine radiological investigations including computerized tomography did not always identify the abnormality; radioactive cisternography can help to establish cerebrospinal fluid leak. All 58 episodes of pyogenic meningitis in these 17 patients with different underlying disease responded to conventional treatment with antibiotics without mortality and without undue morbidity. Surgical procedures in intracranial disease had variable success. Correction of complement deficiency is not practical at present. In some patients prophylaxis with antimicrobial drugs is the only method of preventing future attacks.