The notions of "maturity" and "maturation" of newborn infants are discussed in the context of forensic medical expertise based on the publications of the authors studying this problem. It is suggested that "maturation" should be considered to be a morphological notion in contrast to "maturity" to be regarded as a chronological notion. From this point of view, the solution of the maturity problem during forensic medical examination of the infant's corpse is beyond the scope of competence of the forensic medical expert. The authors emphasize the importance of differentiation between the above notions for the unambiguous interpretation of the results of examination by different experts.