A retrospective study on 357 children admitted to four Pediatric Infectious Disease Centers in Rome, affected by acute meningitis, during 10 years period, between January, 1, 1985 and December, 31, 1994 was carried out. Haemophilus influenzae type b was detected in 110 patients; all children aged between 1 month and 5 years; the maximum incidence (74.5%) was observed in patients under two years. The following diagnostic criteria were utilized: Gram stain of CSF; Latex test on CSF, blood, urine; CSF and blood cultures. The in vitro sensitivity of 65 isolates was tested by using the Kirby-Bauer method. We detected 15.3% of strains resistant to Ampicillin and 1.5% resistant to CAF. We also observed a high number of Hib strains resistant to Erythromycin and Cotrimoxazole. Only one strain Ceftriaxone resistant was isolated, confirming the high in vitro sensibility Hib to III generation cephalosporins that still remain the first choice drugs in Hib meningitis.