Toxicological analysis of hair was used to detect cocaine use in a group of 615 pregnant women. Hair samples were washed, enzymatically digested, and analyzed by radioimmunoassay for cocaine. Positive results were confirmed by gas chromatography-mass spectrometry after a solid-phase extraction. Benzoylecgonine (BZE) and cocaine were detected after derivatization with pentafluoropropionic-anhydride-pentafluoropropanol. Deuterated cocaine and BZE were used as internal standards. This study demonstrated a mean frequency of 1.9% cases positive for cocaine in all the hair samples examined. The positive rate was 6% among women admitted for spontaneous abortion (66 cases), and the positive rate was 1.4% for those who carried to full term (549 cases). These data underline the usefulness of hair analysis for the diagnosis of drug abuse and demonstrate that there is significant use of cocaine in the Italian population.