The safety of out-of-hospital births attended by midwives who are licensed according to international standards has not been established in the United States. To address this issue, outcomes of births attended out of hospital by licensed midwives in Washington state were compared with those attended by physicians and certified nurse-midwives in hospital and certified nurse-midwives out of hospital between 1981 and 1990. Outcomes measured included low birthweight, low five-minute Apgar scores, and neonatal and postneonatal mortality. Associations between attendant and outcomes were measured using odds ratios to estimate relative risks. Multivariate analysis using logistic regression controlled for confounding variables. Overall, births attended by licensed midwives out of hospital had a significantly lower risk for low birthweight than those attended in hospital by certified nurse-midwives, but no significant differences were found between licensed midwives and any of the comparison groups on any other outcomes measured. When the analysis was limited to low-risk women, certified nurse-midwives were no more likely to deliver low-birthweight infants than were licensed midwives, but births attended by physicians had a higher risk of low birthweight. The results of this study indicate that in Washington state the practice of licensed nonnurse-midwives, whose training meets standards set by international professional organizations, may be as safe as that of physicians in hospital and certified nurse-midwives in and out of hospital.