All positive cultures (blood, cerebrospinal fluid, urine) obtained from neonates admitted to our exclusively outborn unit from 1984 to 1994 were reviewed. A total of 6,120 infants were admitted during the study period. Yearly incidence of sepsis (culture-proven) had a median of 6% with a 4%-9% range. Only 5 cases of GBS were found between 1984 and 1993, representing 1.2%(5/417) of all cases of positive cultures for the period. In 1994, the incidence rose to 12% (3/25) (p=0.007). Among the 8 cases of GBS (1.3/1,000 live births) only 2 (25%) were late-onset meningeal forms due to serotype III; the remainder were early-onset pneumonias (serotypes I and II). Two patients(25%) had birth weights ≤ 1500g. The rest were full term. Gram negative microorganisms accounted for 82% of isolates until 1990. Thereafter, gram-positive cocci represented 25-27%, with S. aureus as the most frequently found (52%) in this group. In 1994, GBS accounted for nearly half the cases of gram-positive isolates (3/7). During the first semester of 1995, incidence of culture-proven sepsis was 10% (24/240). Gram-positive cocci were found in 12(50%) infants. GBS was found in 41.6% (5/12), for an overall incidence of 20.8% (5/24) (p=0.0001). Logistic regression failed to disclose any associated or predisposing factors, but showed the increased incidence of GBS sepsis to be independent of the overall rise in gram-positive isolates. These data show that GBS disease, previously very rare in our setting, is rapidly becoming the most frequent cause of neonatal sepsis.