Objectives. To evaluate hemoglobin (Hb) levels in pregnant women from different geographical regions from Peru; to establish anemia and erythrocytocis rates and to establish the role of Hb on adverse perinatal outcomes using the Perinatal Information System (PIS) database of Peruvian Ministry of Health. Materials and methods. Data were obtained from 379,816 births of 43 maternity care units between 2000 and . Anemia and erythrocytocis rates were determined in each geographical region as well as rates of adverse perinatal outcomes. To analyze data the STATA program (versión 10.0,Texas, USA) was used. The results were considered significant at p<0.01. Results. Mild anemia rate was higher in the coast (25.8%) and low forest (26.2%). Moderate/severe anemia rate in low forest was 2.6% and at the coast was 1.0%. In the highland, the highest rate of moderate/severe anemia was in the southern highlands (0.6%). The highest rate of erythrocytocis was found in the central highland (23.7%), 11.9% in the southern highland and 9.5% in the north highland. Severe anemia and erythrocytocis were associated with adverse perinatal outcomes. Conclusions. There are differences by Peruvian geographical region in anemia rates. In the central highlands were found the highest rates of erythrocytocis due to hypoxia effect in the high altitudes; however in the southern highlands, erythrocytocis was lower. Severe anemia and erythrocytosis were associated with increased adverse perinatal outcomes.Objetivos. Establecer la frecuencia de anemia y eritrocitosis en gestantes de diferentes regiones del Perú y la asociación con los resultados adversos perinatales utilizando los datos del Sistema de Información Perinatal (SIP) del Ministerio de Salud (MINSA). Materiales y métodos. Se obtuvieron datos de 379 816 partos de 43 centros asistenciales del Ministerio de Salud entre los años 2000 y 2010. Se determinó la frecuencia de anemia y eritrocitosis en cada región geográfica así como de los resultados adversos perinatales. Resultados. La frecuencia de anemia leve fue mayor en la costa (25,8 %) y en la selva baja (26,2 %). La frecuencia de anemia moderada/severa es más alta en la selva baja (2,6 %) seguido de la costa (1,0 %). En la sierra, las frecuencia más alta de anemia moderada/severa se observa en la sierra sur (0,6 %). La mayor frecuencia de eritrocitosis (Hb>14,5 g/dL) fue encontrada en la sierra centro (23,7 %), seguido de 11,9 % en la sierra sur y 9,5 % en la sierra norte. La anemia severa y la eritrocitosis estuvieron relacionadas con los resultados adversos perinatales. Conclusiones. Hay diferencias por región geográfica en la frecuencia de anemia. En la sierra central se encontró mayor frecuencia de eritrocitosis con respecto a la sierra sur. Tanto la anemia severa como la eritrocitosis aumentan los resultados adversos perinatales.