I reviewed the results of probing for congenital nasolacrimal duct obstruction in a series of 107 patients, with special reference to age at the time of probing. Relief of tearing and discharge was achieved in 90% of patients with the first probing, and an additional 6% were cured after a second probing. Altered nasolacrimal duct anatomy seemed to account for probing failures rather than any delay in probing. Primary probing continued to be an effective treatment well after 2 years of age and was successful in two 5-year-old patients. Unsuccessful probings were usually apparent at the time of the initial probing and were characterized by difficulty passing the probe and subsequent inability to irrigate saline through the nasolacrimal system into the nose. Dacryocystorhinostomy was an effective secondary procedure in the few patients in whom probing was unsuccessful.