Objective: Although long-term pituitary consequences of tuberculous meningitis are well documented in the literature, there have been few case reports of pituitary dysfunction after acute bacteria[ or viral meningitis. In this preliminary study, we have assessed the pituitary functions in adult patients who had acute bacterial or viral meningitis. Design and methods: Fourteen patients (8 men, 6 women; mean age 35.3 +/- 13.3) were included in the study. The diagnosis of bacterial and viral meningitis was proven by clinical findings, cerebrospinal fluid (CSF) examination, gram staining, and blood and CSF cultures. Pituitary functions were evaluated ranging from 6 to 48 months (mean 20 months) after acute meningitis. GH deficiency was investigated by the GHRH+arginine stimulation test. Results: Four of 14 patients (28.6%) had isolated GH deficiency. In GH-deficient patients, the earliest duration was 6 months and the latest duration was 48 months after the diagnosis of acute meningitis. Three of the GH-deficient patients had acute bacterial meningitis and I patient had acute viral meningitis. Pituitary magnetic resonance imaging revealed normal pituitary gland in the patients with GH deficiency. Conclusions: This is the first systematic study evaluating the anterior pituitary function long term after the diagnosis of acute meningitis. Based on the present study, it is tempting to speculate that pituitary dysfunction is a more common sequel of acute bacterial or viral meningitis than hitherto reported. Studies with high numbers of patients are warranted to ascertain the prevalence of meningitis-induced hypopituitarism.