The aim of this study is to compare the administration of 1 unit dose of 100 mg tramadol intravenously versus multiple smaller dosages of tramadol during the first 6 hours post-operatively and to investigate the time course and accuracy of pain relief versus the onset and duration of side-effects.

Inclusion Criteria:

• ASA I and II female or male patients
• Aged 18-70 years
• Scheduled for ambulatory surgery requiring postoperative pain medication.

Exclusion Criteria:

• Weight less than 70% or more than 130% of ideal body weight
• Neurological disorder
• Recent use of psycho-active medication, including alcohol
• Patients suffering from chronic pain receiving pre-operative pain medication including NSAID's
• Use of chronic anti-emetic medication, use of chronic corticoid therapy