Because there are few salmonid farms in Romania where trout are artificially breed, is necessary for them to streamline their te chnological and economic activities, based on a selection-breeding program. Factors that influence the production and reproduction performance of rainbow trout are numerous, one of them being breeding age. Due to this, we aimed to identify the optimal age for use in breeding females of rainbow trout. For this, were randomized retained 20 rainbow trout females with 3, 4, 6, 8 and 10 years age old (20 from each category). They were weighed and measured, being analyzed the breeding performance, like ovary weight, the total number of eggs, egg diameter, egg volume, individual mass of eggs. The obtained data were used to calculate the reproduction indices: gonadosomatic ratio GSr , absolute individual index of fertility - Williams Waif , Behning-fertility coefficient Bfc . Between the values of these indices and the value s of initial phenotypic characters analyzed, were calculated cor relations. The results lead to the conclusion that, in practice, must be used rainbow trout females betwee n the ages of 4 and 6 years. Introduction: In Romania there are few salmonid farms were the artificial reproduction of trout is practiced, being preferred the imports of biological material, as embryonated eggs (Finn, 2007). For those who dealing with artificial reproduction of trout, of great interest is the selection of breeding stock, using several indicators: age, conformation, fertility, growth performance (Pante et al ., 2002; Serezli, 2011). Aims and Objectives. From the perspective of economic efficiency and th e increase of productivity and product quality in Romanian tro ut farms, we propose to do an analysis of the impact of breeding age in rainbow trout females and its effects on fertility indices. Materials and methods: Were performed somatic and gravimetric measurements on rainbow trout ( Oncorhynchus mykiss ) breeding females, from the Fiad-Telcior salmonid complex, Bistri Ńa-Nasaud County. Also, were taken samples of eggs, from each specimen, in part. These were subsequently analyzed. Based on th e obtained data, were calculated the fertility indices (Gonadosomatic ratio GSr , Absolute individual index of fertility - Williams Waif , Behning-fertility coefficient Bfc ) and the correlations between them, different age and phenotypic characters. Results and Discussions. Were analyzed five groups of rainbow trout breedin g females at 3, 4, 6, 8, and 10 years age old. The ob tained results indicate increasing values for all phenotypic characters, directly proportional to the age. For performance and breeding indices, the values were obtained in the form of a Gaussian curve, which shows precisely the optimal age for breeding. In terms of the obtained correlations, they are generally strong between indices of breeding and gravimetric measurements (body weight before and after egg collection): Ibw-Gsr=0.912 (3 years), 0.693 (4 year s), 0.467 (6 years), 0.493 (8 years), 0.585 (10 years), decreasing with age, respectively Fbw-G Sr=0.892 (3 years old), 0.835 (4 years