The implantable pump field is now more than 20 years old. The original goal of developing a totally artificial β-cell remains unrealized, but programmable insulin pumps that contain all of the elements of the artificial β-cell except the glucose sensor are involved in clinical trials in the United States and are commercially available in Europe. Currently, both single-rate and programmable implantahle pumps are in general clinical use in the United States for the treatment of pain and spasticity, cancer, and osteomyelitis. Only a few of the potential applications of implantable pumps have been developed to the stage of commercial availability. This is, in part, because drug companies have traditionally developed parenteral drug applications only as a last resort and, in part, because of the complexity of the regulatory process for implantable pumps, often requiring review by both the drug and device branches of the Food and Drug Administration.