4-Nonylphenol (NP) is considered an endocrine disruptor due to its capacity to interact with endocrine system, mimicking estrogen activity. It is a ubiquitous pollutant since it has been found in many human tissue samples and its precursor identified in sewage, sediments, rivers and drinking water. Thus, this work aimed to evaluate reproductive parameters in female Balb/C mice treated with 50 mg/kg body weight of NP for 21 days, a period in which they reach sexual maturity. Body weight during treatment, day of vaginal opening, organs weight, fertility rate and proportion of different follicle types were some of these parameters. Additionally, for analysis of some effect in littermates, a group of animals underwent two attempts at pregnancy after treatment. NP had no effect on body weight during treatment, nor did it alter the day of vaginal opening and fertility rate of females. The proportion of preantral, antral and degenerated ovarian follicles was not modified by treatment with NP, and no morphological or pathological alterations were observed. The number of pups did not differ between treatments in any attempt at pregnancy. Also the weight of pups on birth and female rate in littermates was similar among experimental groups after both trials of pregnancy. It is suggested that the NP available or accumulated during the period of sexual maturation (21 days) did not reach threshold levels capable of producing significant alterations in the reproductive parameters analyzed.