A study was made of a patient with carcinoma of the hypophisis which invaded the sphenoid bone and made protrusion under the nasopharyngeal mucosa, and that of a patient with craniopharyngeoma. The patients had no symptoms proper to the tumors but presented several episodes of meningitis. The presence of the tumor, in both cases, was evidenced lately, when the failure of the antibiotic therapy became patent leading to the search of intracranial focuses of infection through radiologic examinations. The nature of the leptomeningitic episodes is discussed. Their relation to possible communications between the oropharyngeal cavity and the subarachnoid space, secundary to the changes in the anatomic structures of the region provoked by the tumors, is emphasized since these communications make possible the invasion of the subarachnoid space by bacteria. Although this opinion is acceptable in respect to the cases related, it is not possible to exclude the aseptic nature of meningitic episodes observed as no pathogenic micro-organism was isolated from the CSF samples studied and the necroscopic examination showed no septation in the leptomeningeal structures that surrounded the tumor or no obvious focus of infection related to them. Considering the cases reported the authors point out that radiologic and neuro-radiologic examinations must be indicated, as soon as possible, in order to exclude such tumors in patients suffering from meningitis of obscure origin, specially when its course is delayed and/or marked by acute episodes or re-exacerbation.