Relief of pain, whether post-traumatic or postoperative, is a prerequisite for the prevention of its deleterious effects on the whole organism. Unalleviated pain also increases the victim's or patient's anxiety and apprehension, which in turn increase the intensity of the pain. In the management of pain, opiates have maintained their position as the most common form of analgesic therapy despite the many side effects associated with their use. This double-blind study compared the analgesic effects of low doses of racemic ketamine and the morphine derivative oxycodone on postoperative pain after elective tonsillectomy. Also, the suitability of oxycodone for field use was evaluated with respect to ketamine. Plethysmographic pulse-wave amplitude changes were compared with the pain visual analogue scale scores as measures of postoperative pain. The results of this study did not reveal any significant differences between the analgesic potencies of the studied drugs and clearly demonstrate that even suboptimal doses of both ketamine and oxycodone can provide appreciable relief of pain.