Tissue and organ printing is an evolving technology that uses a special-delivery device (the bioprinter) to deposit self-assembling biological material (the bio-ink) into a three-dimensional biocompatible scaffold (the biopaper) with high spatial accuracy. Delivery of the bio-ink takes place layer by layer according to the anatomical blueprint (that is, the shape and histological composition) of the desired structure. This “blueprint” is obtained by bioimaging—for example, through magnetic resonance imaging (MRI) or ultrasound—the structure to be reproduced and stored in the computer controlling the operation of the printer (Fig. 1). Accordingly, the technology has three main steps: preprocessing, or computer-aided design (CAD) of the organ; processing, the actual printing and fast solidification of tissue and/or organ construct; and postprocessing, accelerated tissue and organ maturation. The overall objective of this technology is to mitigate the chronic shortage of replacement organs by building three-dimensional functional biological structures, or organ modules, of specific shape in the laboratory. Organ printing relies on classical tissue engineering, which is based on the process of seeding cells into biodegradable polymer scaffolds, culturing and expanding the cells in bioreactors for several weeks, and implanting the resulting tissue into the recipient organism. At the same time, the new technology represents a departure from the classical approach in that the seeding of cells is performed by printers and proceeds according to a CAD.