ATP-binding cassette (ABC) transporters are widely present molecular machines that transfer substrates across the cell membrane. ABC transporters are involved in numerous physiological processes and are often clinical targets. Structural biology is fundamental to obtain the molecular details underlying ABC transporter function and suggest approaches to modulate it. Until recently, X-ray crystallography has been the only method capable of providing high-resolution structures of ABC transporters. However, modern cryo-electron microscopy (cryo-EM) opens entirely new ways of studying these dynamic membrane proteins. Cryo-EM enables analyses of targets that resist X-ray crystallography, challenging multicomponent complexes, and the exploration of conformational dynamics. These unique capacities have turned cryo-EM into the dominant technique for structural studies of membrane proteins, including ABC transporters. ATP-binding cassette (ABC) transporters are dynamic and conserved membrane proteins of high clinical interest. Their structural studies have been challenging due to their intrinsic flexibility, size, and requirements for specific membrane environment. Cryo-electron microscopy (Cryo-EM) has opened new avenues to analyze ABC transporters and other challenging membrane proteins. Cryo-EM can provide a direct view on the assembly of the multicomponent complexes. Cryo-EM allows capturing multiple conformations of ABC transporters to gain better understanding of their dynamics and mechanism of action. [ABSTRACT FROM AUTHOR]