Since the early 1980s, the implantable intrathecal drug pump (ITDP) has been used increasingly to manage chronic pain. Prior to making a decision to implant an ITDP, trial administration of the intrathecal (IT) drug should be performed to estimate the effective dose for a starting set of implantable ITDPs. There is no standard method of trial IT drug administration, though. Therefore, this paper reports 20 cases of IT morphine trial with single and repetitive injections until the appropriate dose was attained with respect to analgesia and its side effects. The trial procedure was performed with daily sequential IT injections using morphine and 0.3% mepivacaine. Twelve out of the total of 20 patients had positive responses. Thus, it is inferred that daily sequential IT morphine injections combined with a placebo injection as a trial ITDP would be useful in evaluating the effectiveness and adverse effects of IT morphine infusion with clinically insignificant side effects. (Korean J Anesthesiol 2011; 60: 138-141)