The aim of this study was to investigate the glaucoma control of latanoprost therapy in primary congenital glaucoma (PCG) and assess the factors affecting long-term outcome. Eighty-one eyes of 44 patients with PCG and 42 eyes of 29 patients with previous glaucoma surgery that had been treated with latanoprost as primary treatment were included, with age at treatment varying from 1 to 34 months. Patients were re-examined at a study visit to evaluate intraocular pressure, length of glaucoma control with latanoprost, need of further medication or glaucoma surgery, systemic and topical side-effects. In the first group, a success (glaucoma control by latanoprost therapy) was found in 24 eyes (29.6%), whereas 57 eyes (70.4%) had received surgery (45 eyes (55.6%) in the first year); among the eyes with previous surgery, a success was found in 12 eyes (28.6%), 13 eyes (31%) required an additional therapy and 17 eyes (40.5%) had received further glaucoma surgery. No patient discontinued the treatment because of side-effects. Factors related to the failure of the latanoprost treatment were: the high score of severity of glaucoma (P=0.014) and low age at PCG presentation (P=0.042). The authors concluded that long-term treatment with latanoprost is effective in about 30% of the eyes. Factors related to poor glaucoma control included severe glaucomatous alterations and young age at presentation.