Terminally ill cancer patients commonly suffer from several symptoms at the same time, such as pain, nausea, anxiety, cognitive failure, bowel obstruction, and fatigue. To obtain optimal symptom control, the simultaneous administration of more than one drug by continuous subcutaneous (SC) infusion is often required. Tramadol is considered an effective step II agent of the World Health Organization's analgesic ladder for the control of chronic pain conditions, including neuropathic pain, and also exhibits a good safety profile. Haloperidol has been found to be very efficient in controlling agitation with or without pain, nausea and/or vomiting of central origin, intestinal obstruction, and delirium. Although the combination of tramadol and haloperidol in the same solution for SC infusion may be desirable, the physicochemical stability of this combination has not yet been documented. Therefore, our aim was to study the physicochemical stability of drug admixtures composed of tramadol hydrochloride and haloperidol lactate, which have been stored in polypropylene syringes at 4 degrees C and 25 degrees C, and assayed at 0, 5, 7, and 15 days after preparation.