Using a new computerized methodological procedure a separate analysis and a quantitative determination of the viscous and elastic parameters of the scalp hair shaft were performed in 37 neonates of both sexes with a gestational age of 28-29 weeks (n = 16) and 39-40 weeks (n = 21), respectively. A statistically significant (p < 0.001) decrease in the values of modulus of elasticity (E alpha) was found in the hair shaft of premature neonates, as compared to the full-term ones, whereas the values of post yield slope (E beta) and of SDIS/SSTOR (viscous parameter) did not significantly differ in the two groups. The decrease in modulus of elasticity in the hair shaft of premature neonates may be interpreted in terms of an insufficient number of disulphide bonds between the alpha-helical keratin units of the hair cortex or of a disordered arrangement of microfibrils within the matrix. Further studies are now warranted to determine the pattern of mechanical parameters of the scalp hair shaft in large numbers of newborn infants of different gestational ages and to answer the question as to whether this pattern might be useful in the accurate postnatal assessment of fetal maturation.