BACKGROUND Intra-articular corticosteroid injections (IACI) are routinely used by pediatric rheumatologists in the treatment of chronic arthritis. Frequently, topical anesthetics are used to control procedural pain, but their relative efficacy has not been reported. In this study, we evaluated the level of pain associated with different anesthetic methods, Numby® 900 Iontophoretic Drug Delivery System, or EMLA® cream, with or without subcutaneous buffered lidocaine (SQBL), during IACI of the knee in children with arthritis. METHODS We conducted a prospective study of patients, ages 4 to 21 years old, followed at three pediatric rheumatology centers who were undergoing IACI of a knee joint. Patients were randomized into two treatment groups: 1) topical anesthetic only (EMLA® or Numby® (E/N)), or 2) topical anesthetic (E/N) and SQBL. Pain was assessed at baseline, during topical anesthetic placement, and following the IACI (post-procedure). The Faces Pain Scale-Revised (FPS-R), the Face, Leg, Activity, Cry, Consolability (FLACC) behavioral scale and the parental global assessment (PGA) (0 = best experience, 10 = worst experience) were determined. RESULTS Sixty-three patients (44 females) with a median [IQR] age of 10.8 [IQR = (8.2-14.4)] years (range 4.7-20 years) with active knee arthritis were consented. FPS-R post-procedure (P = 0.03), FLACC (P = 0.02) and PGA (P = 0.01) scores were significantly lower in females treated with E/N plus SQBL compared to patients treated with E/N only. Females in the E/N only group had a significant worsening of their baseline pain (p < 0.0004) and a greater magnitude of change in their baseline FPS-R scores (p < 0.001) from the procedure compared to females in the E/N plus SQBL group who had no worsening of their baseline pain. No significant change in pain level or PGA score was found among males in either treatment group. Pain scores overall were similar to the oligoarthritis patients, a more homogeneous group of patients. Both EMLA® (n = 33) and Numby® (n = 29) were equally well tolerated with no significant difference in median FPS-R administration scores overall. CONCLUSIONS Our results suggest that a topical anesthetic plus SQBL is more effective for injection pain control than topical anesthesia only. Further studies addressing pain and anxiety will help determine the optimal method of pain control for IACI.