Adequate control of side effects during medical treatment of cancer increases patient compliance and quality of life. Antiemetic drugs are not an effective treatment for the one in three cancer patients on chemotherapy who experience anticipatory nausea and vomiting (ANV); the behavioral treatment of systematic desensitization has been found effective for ANV when delivered by clinical psychologists. This study examined the effectiveness of systematic desensitization when delivered by medical personnel versus clinical psychologists. Seventy-two consecutive cancer patients with ANV were randomly assigned to no-treatment control or to systematic desensitization from 5 behaviorally trained clinical psychologists, 6 clinical oncologists, or 10 oncology nurses. The treatment was found effective in reducing anticipatory nausea, anticipatory vomiting, posttreatment nausea, and posttreatment vomiting compared to control patients, with no significant differences in effectiveness found between clinical psychologists and oncology staff. Although medical personnel should not engage patients in psychotherapy or other interventions that cannot be completed successfully, they can treat patients effectively with systematic desensitization and should be encouraged to learn and use this and other behavioral intervention techniques to benefit total patient care.