Pain is a common problem for people living with cancer. A particularly challenging therapeutic dilemma may present itself when a patient with substance abuse presents clinically with cancer pain. The feature and goal of palliative care is to prevent and relieve suffering and to improve quality of life for people, including who with substance abuse. In these patients who live with life-threatening diseases, a remote or current history of drug abuse presents a stigmatizing issue that can complicate the management of underlying diseases and palliative therapies. Treatment options may be uncertain due to myths which exist about therapy for patients with substance abuse. This article reviews the literature and discusses strategies of pain evaluation of patients with substance abuse.