This invention is related to the use of polyurethane based polymer as a drug delivery device to deliver biologically active compounds at a constant rate for an extended period of time and methods of manufactures thereof. The device is very biocompatible and biostable, and is useful as an implant in patients (humans and animals) for the delivery of appropriate bioactive substances to tissues or organs. The drug delivery device for releasing one or more drugs at controlled rates for an extended period of time to produce local or systemic pharmacological effects comprises: 1. a reservoir, said reservoir comprising; 2. at least one active ingredient; and, optionally, 3. at least one pharmaceutically acceptable carrier; a polyurethane based polymer completely surrounding the reservoir.