Tone decay was studied in a group of 17 profoundly deaf adults who have a single-channel cochlear implant. With direct electrical input through the subject's induction coil system, tone decay was evaluated at 125, 250, 500, 2 000, 4 000, and 16 000 Hz. Results indicated that as the intensity of electrical stimulation increased, the ability to perceive a continuous signal also increased for the majority of the subjects. All but 3 of the subjects were able to perceive the electrical signal at suprathresholds for 2 min. The 3 subjects who exhibited tone decay differed from the rest of the sample in several ways: (1) they became deaf at an earlier age; (2) they had more years of profound deafness, and (3) they had fewer years of cochlear implant and hearing aid use.