Objective: The objective of the study was to determine the rate of early onset group B streptococcus (EOGBS) infection in Utah and identify potential areas of failure in EOGBS prevention.Study Design: We queried the microbiology records of Intermountain Healthcare for infants with culture-confirmed EOGBS between 1 January 2002 and 31 May 2006 and calculated rates of EOGBS per 1000 deliveries. We reviewed the infant and maternal records of each EOGBS case to identify possible failures in EOGBS prevention.Result: There were 54 cases of EOGBS among the 127 205 births (0.42/1000 births). Of all, 12 were preterm. Of the 39 (93%) women prenatally screened for GBS, 31 (79%) had negative results and 7/8 (88%) women with positive prenatal GBS screens either did not receive intrapartum antibiotic prophylaxis (IAP) or received inadequate IAP. Of the 54 infants with EOGBS, 3 (6%) died.Conclusion: Utah's rates of EOGBS were higher than the national average. Factors associated with EOGBS include missed screening opportunities, inadequate IAP, and false-negative maternal GBS culture.