Eleven black rhinoceroses were successfully immobilized, ten of them in the Arusha Chini area of Tanzania and one, a penned animal, near Nairobi. Of the total number, two were immobilized with Etorphine hydrochloride (M. 99) and acetylpromazine; six with a combination of Etorphine, acetylpromazine and a new tranquillizer, Azaperone; and three with Etorphine and Azaperone. In addition, one attempt at immobilization with a relatively new analgesic, Fentanyl, was not satisfactory at the dosage used, the animal being immobilized later with Etorphine and included in the eleven rhino described. Injection was accomplished on the ten Tanzania animals with Cap-Chur equipment from a helicopter, and on the penned animal with a hand syringe. Specimens and data were collected from the immobilized rhino. They were then loaded into crates, given an antidote (nalorphine hydrobromide) intramuscularly, and then trucked to points of release or to holding pens. Immobilization data, weights, sexes, relative ages, rectal temperatures, respiratory rates and pulse rates are tabulated.