This study compared the effectiveness of a new topical anesthetic, tetracaine-lidocaine-phenylephrine (TetraLidoPhen), with that of lidocaine infiltration during repair of mucous membrane lacerations in children. It was conducted in the emergency department of an urban children's hospital with use of a prospective, randomized, blinded study design. Participants were 90 children 1 year of age or older with a laceration 5 cm or less in length on or near a mucous membrane that required suturing. They were randomly assigned to one of two treatment groups, with 45 patients in each group. Pain felt during suturing was scored by suture technicians, research assistants, a videotape reviewer, parents, and patients 5 years of age and older using a Visual Analogue Scale (VAS). Suture technicians, research assistants, a videotape reviewer, and parents also scored pain using a seven-point Likert scale. In addition, suture technicians completed an Anesthesia Effectiveness scale and a Wound Blanching scale. The laceration was located near the eyes in 71 patients (79%), and on or near the lips in 19 (21%). Lidocaine infiltration performed significantly better than topical TetraLidoPhen in comparisons of Likert scores of suture technicians (P = 0.007), research assistants (P = 0.005), the videotape reviewer (P = 0.003), and parents (P = 0.03); Anesthetic Effectiveness scale scores of suture technicians (P = 0.00002; relative risk (RR) = 1.83, 95% confidence interval 1.36 < RR < 2.46); and VAS scores of suture technicians (P = 0.002), research assistants (P = 0.001), and the videotape reviewer (P = 0.005). No significant difference in performance was detected between lidocaine and TetraLidoPhen in comparing VAS scores of parents and patients. There was a 4.4% wound complication rate, including two (2.2%) wound infections. The authors conclude that TetraLidoPhen is a new topical anesthetic that appears to be safe when applied on or near mucous membranes. Its performance among study participants was statistically inferior to that of lidocaine infiltration; however, the differences in pain scores were small and may not be clinically significant. Also, comparisons of pain scores in this study did not take into account the pain associated with the initial injection of lidocaine. Therefore, study findings may underestimate the comparative performance of TetraLidoPhen. Further investigation of this new topical anesthetic is warranted.