Four useful procedures for preparing a series of new 2-pyridyl-4(3H)-quinazolinones were investigated and twelve quinazolinones were evaluated for hypnotic activity. Some of them showed a definite hypnotic effect in intraperitoneal doses above 100 mg/kg, whose structure-activity relationship demonstrated that 3-pyridyl and 4-pyridyl substitution at 2-position of 4 (3H)-quinazolinone ring and ο-fluorophenyl and ο-chlorophenyl at 3-position are appropriate for the manifestation of hypnotic activity. A maximum hypnotic effect was observed in 2-(4-pyridyl)-3-(ο-fluorophenyl)-4(3H)-quinazolinone (1), the potency of which was equal to methaqualone in mice.