 Peptids are short chains of amino acids linked by peptid bonds, but their poor enzymatic stability and permeability across the intestinal epithelial membranes and blood-brain barrier, BBB, make parental administration unfavorable. Instead, oral delivery is preferred because it allows for self-administration and high patient acceptability and compliance. However, this poses a major challenge as peptid drugs must overcome physical and biochemical barriers of the gastrointestinal tract and BBB. Active targeting ligands and cell-penetrating peptids can increase penetration and uptake across the BBB, and diverse combinations of drug delivery systems, active targeting ligands, and cell-penetrating peptids are used to deliver peptids to the brain. This article was authored by Murad Al-Gailani, Mengyang Lu, and Jingyuan Wen.