This present study investigated the effects of intraarticular morphine administration in 1mg and 5mg doses on post-operative pain relief and analgesic requirements for patients undergoing arthroscopic procedures. At the end of the operation patients were randomly allocated in a double-blinded fashion into three groups. The control group (Group 1) received normal saline 20 mL intraarticularly. The patients in the second and third groups received intraarticular morphine sulphate 1 and 5mg in saline 20 mL, respectively. Post-operative pain was assessed on the 1st, 6th and 24th hour by visual analogue scale (VSA). Supplementary analgesic requirement and possible complications were also followed. The intensity of pain and analgesic requirement were reduced more in the morphine 5mg group than in the control group. It is concluded, that the administration of intraarticular morphine 5mg provides long-lasting and effective analgesia after knee arthroscopy.