Evaluations of weight and cephalic perimeter are very used to study the growth and development in human beings. Similar measures, called murinometrics, have been an efficient resource to study the effects of nutritional and pharmacologic manipulations on the somatic development in rat. The aim of this study is to describe a method of evaluation which offers a higher accuracy in the collect of data in the study of somatic development in Wistar rat. Measurements were realized in latero-lateral axis of skull; Antero-posterior axis of skull; Longitudinal axis; Length of tail in 60 wistar rat during breastfeeding period. The most suitable method of measurement respects predetermined anatomic points, the use of the suitable scapus of pachymeter as well as its accuracy