Two hundred and seven healthy newborns, 35 to 42 weeks of gestationl age (GA) determined by strict criteria, were prospectively studied. Mid arm circumference (MAC) in left arm was measured between 25 and 72 hours of age. Birth weight (BW), lenght (L), and head circumference (HC) were obtained from each baby's codified chart. Ponderal index (PI) was calculated. Linear correlation (r) values were for MAC vs BW + 0.85; MAC vs L + 0.70; MAC vs GA + 0,48; MAC vs PI +0.50 and BW vs GA +0.56. In the MAC vs G A values there was also a great variability; specially over 38 weeks of GA. The same occurs for BW vs GA and L vs GA. It is concluded that in this study, MAC correlated very well with BW being useful to evaluate nutritional status. MAC showed a poor correlation with GA, which differs from previously published studies. (Key words: Mid-arm circumference, head circumference, ponderal index, fetal growth, intrauterine growth retardation, fetal macrosomia.)El perimetro braquial (PB) y la razon perimetro braquial/circunferencia de craneo (PB/CC) han side ampliamente utilizados en el lactante mayor de 3 meses y en el preescolar y escolar. Se ha demostrado que estas mediciones son buenos indicadores del estado de nutrition y que complementan a las mas clasicamente empleadas, como el peso, talla, circunferencia craneana y la relation entre estas ultimas 1 . Asi tambie"n, Frisancho ha publicado tablas patron de referenda de crecimiento a partir del ano de edad, utilizando pliegues cutaneos (tricipital) y perimetro braquial 2 .El empleo de estas mediciones en el recien nacido (RN), tendria la vemaja de identificar mejor a los nifios con alteraciones en el crecimiento intrauterino, que presentaran mayor riesgo en el periodo neonatal, y en segundo lugar de ser un metodo facil y no invasive de seguimiento del estado nutritivo postnatal en el RN