In the present study the relevant texts in the Hebrew Bible concerning sacrifice or redemption of the first born of humans and animals are considered in detail. The most important findings are the following: 1. An Israelite could understand the instructions in Ex. xxii 28f. to mean that he should sacrifice his first-born child to JHWH. 2. Ez. xx 25f. describes such first-born sacrifices for JHWH as practised. Therefore it cannot be ruled out that in early Israel at a particular time such a sacrificial practice could indeed have occurred. 3. In the laws of the first-born in the Book of Covenant, in the Dodecalogue and in the original layer of Num. xviii 15-18 (P) the corresponding terms bekôr and peter rekhem refer to the male and female first-born of human and animal. The regulation in Deut. xv, to consecrate only the male first-born clean animals to JHWH and to consume them in JHWH's presence during the Feast, is connected with a clearly farmer-friendly tendency of the deuteronomic law-maker. Apart from that a limitation to the male first-born prevails only in the later post-exilic period. According to the note in Num. xviii 16, the redemption of the human first-born applies only to male children; according to the law of the first-born in Exod. xiii only the male first-born of human and animal (of female Israelites and animals) are affected.