The incidence of macrosomic newborns and fetal death and its possible relation to maternal diabetes mellitus (DM) was registered during six months at the Hospital de Ginecoobstetricia "Dr. I. Morones", IMSS. Both criteria for macrosomia 4,000 g and 4,500 g, were taken for data collection. We had a total of 15,217 newborns, of these, 872 (5.73%), weighed > 4,000 g, and there were 42 mothers with DM, 4.2% of the group. Taking 4,500 g as criteria for macrosomia, there were 105 newborns (0.69%) of the total and there were 8 mothers with DM, 7.6%. 501 of the pregnancies finished by cesarean section and 337 by delivery. There were 151 fetal deaths, 9.9 for 1,000 newborns, eight fetuses had a weight over 4,000 g, and two mothers had DM. It is concluded that maternal diabetes mellitus occurred in less than 5% of the mothers with macrosomic newborns (> 4,000 g). The incidence of macrosomia is lower than in European populations. Fetal deaths were higher than expected because this hospital concentrates patients with obstetrical complications.