In the management of congenital nasolacrimal duct obstruction (CNDO), there is not a well-established agreement about the proper time for probing. Some authors perform it prior to the first year of life, since after this age the relapse frequency would be very high; others prefer conservative management, since they deny this high frequency. In order to evaluate which one of these two opinions has to be considered more appropriate, the present study retrospectively reviewed the frequency of relapses at the 6-month-mark after surgery in 77 patients (40 males, 37 females) probed for CNDO at the Children's Hospital of Trieste in the 1990-1992 period. In our case-record relapses were found in 7.8% of all patients (8.8% of eyes), while the corresponding percentages were 10.8% of patients (14.3% of eyes) in those probed in the first year of life, 5% of patients (3.8% of eyes) in those probed after this time. These results show no worsening for late probing outcome, with respect to early probing. As a consequence of these findings, it can be recommended that for CNDO it is proper to start with a conservative management, represented by lacrimal sac massage and antibiotic eye drops instillation, if mucopurulent discharge is present, for a 4-6 weeks period. If symptoms do not disappear completely after this period, whether probing is the treatment of choice, possibly after the 6th month of life, or, when parents prefer this option, to resume the medical treatment, since also late probing guarantees a good outcome. The choice for probing is mandatory after second year of life.