Osteopenia of preterm newborns is a condition of undermineralization which arises during the first years of life in very low birth-weight infants. The pathogenesis of disease is multifactorial, even if its main mechanism is the inadequate mineral intake (overall the inadequate phosphorus intake). A wide spectrum of signs and symptoms may be observed ranging from overt rickets to asymptomatic conditions. Diagnosis is usually based on either photon or biochemical findings (hypophosphoremia, hyper calciuria, hypophosphaturia). There is not agreement about the prevention and the treatment and about the benefit of any form of mineral supplementation. The aim of our study is a review of the recent studies concerning the osteopenia of prematurity to focus this new problem.