Repeat probing of the nasolacrimal duct is one treatment option for children with persistent symptoms of nasolacrimal duct obstruction (NLDO) following an initial probing. The authors conducted a prospective, multicenter study in which 20 subjects age 6 to <48 months underwent a repeat probing for symptomatic NLDO and had follow-up visits 1 month and 6 months after surgery. Treatment success was defined as the absence of all three clinical signs of nasolacrimal duct obstruction-epiphora, increased tear lake, and mucous discharge. Repeat probing was successful in 56%(95% CI, 33%-76%) of cases.