OBJECTIVE: To evaluate some of the risk factors for neonatal asphyxia in neonates weighing more than 1000 grams. METHODS: In a population of 13.385 consecutive deliveries, from January 1991 to December 1994, 135 newborns with neonatal asphyxia were compared with 135 without the disease, in a casecontrol study, matched by birth weight, at the Neonatology Unit of the Pediatric Department of the Universidade Estadual de Campinas (UNICAMP). The statistical analysis employed was bivariate and multiple by logistic regression, and expressed as odds ratio (OR) with 95% confidence intervals. RESULTS: In the bivariate analysis, the factors significantly associated with asphyxia were: abruptio placentae [OR = 8.00 (1.07-353.4)], cesarean section [OR = 2.94 (1.64 -5.55)], breech presentation [OR = 3.33 (1.54 - 7.98)], abnormal fetal heart rates [OR = 4.88 (2.25-12.08)], prolonged rupture of membranes [OR = 4.33 (1.19-23.71)], a meconial hemorrhagic or infected amniotic fluid [OR = 9.00 (3.58 - 29.03)], oligohydramnios or polyhydramnios [OR =5.00 (1.88 - 16.76), use of anesthesia [OR = 2.56 (1.41 - 4.89)] and general anesthesia [OR = 14.00 (2.13 - 598.8)], male sex [OR = 2.06 (1.12 - 3.92)] and a gestational age of less than 37 weeks [OR = 3.29 (1.37 - 9.07). After multiple analysis, abnormal amniotic fluid, oligohydramnios or polyhydramnios, and anesthesia were the only factors associated with neonatal asphyxia, and more than six prenatal visits was a protector factor. CONCLUSIONS: Obstetrical, perinatal and neonatal clinical events are associated with neonatal asphyxia, that concerted efforts to provide adequate prenatal care, optimal assistance during delivery and birth, and appropriate neonatal intensive care should significantly reduce neonatal morbidity and mortality.