Congenital glaucoma is a potentially blinding disease that requires surgical therapy. This paper describes the outcome of trabeculotomy in primary congenital glaucoma.Thirty-nine eyes of 22 children with congenital glaucoma who underwent trabeculotomy with or without a simultaneous trabeculectomy between 1992 and 1997 were retrospectively analyzed.Mean follow-up was 24.7+/-17.9 months. A mean of 1.3 operations per eye were performed. The mean IOP at the end of follow-up (n=39) was 17.7+/-6.0 mmHg; in 8 eyes (20.5%) the IOP was >21 mmHg, in 31 eyes (79.5%) it was < or =21 mmHg. The mean difference between pretreatment IOP and IOP at the end of follow-up (n=39) was -10.5+/-9.4 mmHg (-37.2%). Success rates were calculated: IOP was < or =21 mmHg in 36/39 eyes (92.3%) after 1/2 year of follow-up, in 25/27 eyes (92.6%) after 1 year, in 15/18 eyes (83.3%) after 2 years, in 8/12 (66.7%) eyes after 3 years, in 4/8 eyes (50%) after 4 years and in 4/4 (100%) eyes after 5 years of follow-up. Complications included hypotony (three eyes), subchoroidal bleeding (one eye ), detachment of Descemet's membrane (one eye) and macular pucker (one eye in which later mitomycin C was used). Visual acuity (VA) was tested with various methods in 35 eyes. VA was within the normal nomogram range in 12 eyes and below the normal range in 23 eyes at the end of follow-up. Axial length measurements showed normalization according to the age nomogram in 22 of 35 eyes.This study shows that trabeculotomy is an effective surgical procedure in congenital glaucoma with satisfactory success rates up to 5 years of follow-up.