Background : The objectives were to study whether EMLA or placebo cream could reduce pain during extracorporeal piezoelectric shock wave lithotripsy (EPSWL) using the Piezolith 2300 and to determine which of the components of the application i.e. the occlusive dressing, the cream or the local anesthetics reduced pain.Methods : Two hundred and two ambulatory patients, 125 males and 77 females, ASA I and II subjected to EPSWL were randomly allocated into 5 groups to receive (A) nothing on the skin (control), (B) plastic occlusive dressing, (C) placebo cream and plastic occlusive dressing, (D) EMLA cream and plastic occlusive dressing which were left immersed under water throughout the procedure, (E) EMLA cream and plastic occlusive dressing for 60 min to achieve cutaneous anesthesia and removed before EPSWL.Results : Patients in the group the had either placebo (group C) or EMLA cream (group D) under occlusive dressing had less pain than patients in the control group while those who had only plastic occlusive dressing or cutaneous anesthesia (EMLA cream dressing removed before EPSWL) had no difference in pain score from the control group.Discussion : EMLA or placebo cream under an occlusive dressing on the skin at the area of the entry of the shock wave and left immersed in water throughout the procedure behaved as a coupling medium facilitating transmission of the shock wave through skin, reducing energy reflection and absorption and hence reducing skin trauma and pain. This procedure provides a simple, safe and economical method of pain relief for patients subjected to EPSWL without causing any side effect.