This study was designed to evaluate the pain perception during injection of dental anesthesia using the buffered lidocaine with epinephrine 1:100,000 by 8.4% sodium bicarbonate solution and the unbuffered lidocaine with epinephrine 1:100,000 in children.Twenty five healthy Egyptian children from both sexes with age range of 5-9 years old were enrolled in this study, selected from outpatients clinic at Department of Pediatric Dentistry and Dental Public Health, Faculty of Oral and Dental Medicine – Cairo University.Criteria of selection:The children were selected to fulfil the following criteria:1) Children aged 5-9 years old.2) Apparently healthy children with no systemic diseases, neurologic disorders or mental disabilities.3) Cooperative children (Frankl rating 3 and 4 ) .4) Children with carious bilateral maxillary primary molars.5) Children who are not allergic to the amide group.6) No periapical or gingival legion or gingivitis.Each child received two anesthetic infiltration injections on two separate appointments, once with commercial lidocaine with epinephrine 1:100000 and once with lidocaine with epinephrine 1:100000 which was alkalinized by 8.4% sodium bicarbonate solution using insulin syringes by a ratio of 9:1. Pain during injection was evaluated using the Faces Pain Scale – Revised by showing the scale to the child after each injection and asking him/her to choose a face that best described his/her feeling.Data were collected and statistically analyzed. The difference in pain during injection between the buffered and unbuffered lidocaine was evaluated. Also results were evaluated regarding the age and gender.