Youngest son of Aaron by Elisheba (Ex. vi. 23). Together with his father and three brothers he was consecrated to the priesthood (ib. xxviii. 1; Lev. viii. 13). On the death of Nadab and Abihu, Ithamar and his elder brother, Eleazar, were ordered not to mourn for them; and he and Eleazar were appointed successors of Aaron in the priesthood (Lev. x. 6-15; Num. iii. 4). During the wanderings of the Israelites in the wilderness, Ithamar was the superintendent of the Gershonites and Merarites, who were in charge of the Tabernacle and its equipment, and he directed the service of the Levites (Ex. xxxviii. 21; Num. iv. 21-33). The high-priesthood passed over into the family of Ithamar through Eli, and from him descended in regular succession until Abiathar was deprived of it by Solomon; the high-priesthood then reverted to the family of Eleazar (I Kings ii. 27, 35). In the reign of David, as the descendants of Eleazar were more numerous than those of Ithamar, the latter were appointed for the monthly services in the proportion of one to two of the former (I Chron. xxiv. 3, 4).