Quazepam, a recently introduced long-half-life benzodiazepine, seems to have a more specific hypnotic activity and a physiological mechanism of action. The present study evaluated clinical efficacy and eventually rebound symptoms after the treatment with quazepam and triazolam. Sixty-five patients, affected by sleep disorders, were entered into the study. Patients were treated with a placebo for four days and, if no amelioration of insomnia was observed, they were allocated randomly to receive 15 mg of quazepam (32 patients) or 0.5 mg triazolam (33 patients) for eight weeks and finally the placebo for another week. The sleep quality, the sleep efficacy, the unwanted effects and the rebound effects had been assessed by specific evaluation scales. Both of the drugs showed a hypnogenic efficacy but patients treated with quazepam had significantly less night awakenings; at the treatment's interruption, only the patients treated with triazolam had longer awakenings and rebound symptoms. In conclusion, quazepam seems to have a good hypnotic effect without inducing rebound effects. On the contrary, triazolam turned out to be just a hypnoinducent drug with higher risks of rebound effects after withdrawal.