ood-derived bioactive peptides can be released during digestion and have a potentially beneficial effect on human health. It is known that the penetration of peptides across the small intestine can take place in several ways. The research related to the bioavailability of peptides develops dynamically, but still raises many doubts. Since there are many barriers to absorption of peptides, there is still a need to carry out in vitro and in vivo investigations on the bioavailability of these compounds. Moreover, there are few in vivo studies regarding the absorption and activity of peptides in organs, hence the lack of unequivocal and reliable information about this process. Therefore, this review discusses the current research on in vitro and in vivo absorption of these compounds and factors that play a key role in this process and provides better understanding of the in vitro and in vivo bioavailability and bioaccessibility of peptides.