Strands of hair were simultaneously sampled from both neonates and mothers by cutting with small scissors close to the scalp. Hair was decontaminated in dichloromethane and homogenized, and nicotine was extracted in diethyl ether. After separation on a capillary column, nicotine was identified and quantified by gas chromatography/mass spectroscopy using selected ion monitoring. In all cases, nicotine was found in neonatal hair and in the hair of corresponding mothers. Nicotine levels ranged from 0.15 to 11.80 ng/mg for neonates and from 0.37 to 63.50 ng/mg for mothers. It was possible to establish a significant correlation between both concentrations; this correlation coefficient was 0.83. Findings suggest the possibility of monitoring the transfer of maternal nicotine through the placenta by measuring nicotine concentration in neonatal hair. 21 references and 1 figure