Recent progress in analyzing the structures and functions of G-protein coupled receptors (GPCRs) including β-adrenoceptors (β-ARs) has been made by pharmacological, physiological and molecular biological techniques. The three-dimensional (3D) structures, interaction sites with ligands and conformational changes of these receptor subtypes due to ligand binding are now better understood by the simulation of these receptors using computer-aided molecular modeling. Based on these techniques, numbers and conformations of amino acid sequences of each subtype (β₁-, β₂- and β₃-ARs) were defined and also interaction sites or modes of interaction between ligands and β-ARs could be analyzed three-dimensionally. In addition, simulation of 3D structures of β-ARs by molecular modeling could clearly determine the limited size, space or pocket for fitting with ligands. These studies will give some clues for the clarification of other GPCRs. Thus, this review summarizes current findings on chemical structures of ligands, amino acid sequences, 3D structures and important amino acids of β-AR subtypes for interacting with ligands obtained from mutagenesis, chimeric studies and molecular modeling techniques.