The feeling of pain as a result of orthodontic tooth movement is one of the most cited negative side effects associated with orthodontic treatment. Pain intensity ranges from a slight soreness to a severe constant, throbbing pain. The purpose of the present investigation was to assess pain experiences during the initial stages of orthodontic treatment in terms of level and duration. Also to relate these assessments to the different age ranges. The subject material comprised 45 female patients with an age range of 11 - 39 years with Class I, crowding. All patients were treated by extraction four first bicuspids with the Straight-wire technique 0.018''x 0.025" Roth prescription system. Subjects were divided into 3 equal groups based on their age. Following the placement and ligation of the first archwire (Nickel titanium 0.014" alloy archwire) subjective assessments of pain were made by means of a 100-mm visual analogue scale (VAS) after two hours and then every 24 hours over the first 7-days. Results revealed the following: 1- All patients experienced pain during treatment. 2- Pain was initiated in the majority of cases after 2 hours and peaked after 24 hours in 100%of cases then descended by the third day. The feeling of pain as a result of orthodontic tooth movement is one of the most cited negative side effects associated with orthodontic treatment. Pain intensity ranges from a slight soreness to a severe constant, throbbing pain. The purpose of the present investigation was to assess pain experiences during the initial stages of orthodontic treatment in terms of level and duration. Also to relate these assessments to the different age ranges. The subject material comprised 45 female patients with an age range of 11 - 39 years with Class I, crowding. All patients were treated by extraction four first bicuspids with the Straight-wire technique 0.018''x 0.025" Roth prescription system. Subjects were divided into 3 equal groups based on their age. Following the placement and ligation of the first archwire (Nickel titanium 0.014" alloy archwire) subjective assessments of pain were made by means of a 100-mm visual analogue scale (VAS) after two hours and then every 24 hours over the first 7-days. Results revealed the following: 1- All patients experienced pain during treatment. 2- Pain was initiated in the majority of cases after 2 hours and peaked after 24 hours in 100%of cases then descended by the third day.