Premature thelarche is usually considered a benign condition that disappears without influencing statural growth nor the timing of puberty. It is generally held a phenomenon of endogenous origin but exposure to oestrogenic pollutants must also be taken into consideration since environmental and epidemiological studies have shown that humans and some animal species are adversely affected by environmental chemical substances that interfere with the endocrine system and are known as endocrine disrupters. Environmental pollutants acting as endocrine disrupters include oestrogens and oestrogen-like products that are universally present in the form of hormones used in stockbreeding, chemicals employed in industry and agriculture, and substances naturally contained in plants and cereals. So far few studies have examined the influence of exogenous oestrogenic or oestrogen-like substances in premature thelarche, and there have been equally few reports of the occurrence of many cases in a circumscribed environment and a limited period of time. Since many agents are in a position to make a contribution to the biological mechanisms underlying thelarche, there is no easy way of determining the role of a given substance in the onset of the clinical picture. Furthermore, it must not be forgotten that both the metabolic clearance rate and the serum levels of oestradiol in healthy prepubertal children are still uncertain and even very low doses of exogenous steroid hormones might thus have significant biological effects. Aim of the work is to underline the importance of the exposure to oestrogenic environmental pollutants as possible cause of premature thelarche.