BACKGROUND Congenital toxoplasmosis (CT) is the most frequently encountered congenital infection. The aim of the present review is to report about the long-term outcome of functional and morphological manifestations after an early confirmation of the diagnosis. METHODS We report on a cohort of patients with serologically confirmed CT, born between 1988 and 2001, who were followed up prospectively at a single centre (Institute of Parasitology, Hôpital de la Croix Rousse, University of Lyon). All patients underwent regular ophthalmological, parasitological and paediatric controls on a half-yearly or annual basis. Ocular manifestations were documented and visual acuity was assessed as far as was possible. RESULTS 1,506 seroconversions were diagnosed during pregnancy, and 327 of the live-born offspring were seropositive for CT. At the end of the study period, ocular manifestations occurred in 79 of the children (24 %), and in 7 cases (9 %) they were discovered during the first month of life. In 72 of the patients (91 %), the ocular manifestations developed between 1 and 151 months (median follow-up time: 6.3 +/- 3.7 years; range: 0.5 - 14 years) under medical treatment for the first year of life. At the end of the study period, information regarding visual acuity was available for 66 patients. In 55 of these (83 %), visual acuity was normal in both eyes, and in 11 (17 %), it was reduced below 0.5. In 1 child, both eyes were functionally affected, one severely. CONCLUSIONS CT may not become manifest ocularly until after a decade, which underlines the necessity for long-term ophthalmological monitoring of the infected individuals. In our patients, the prognostic outcome after therapy for the first year of life was better than that reported in the literature. This favourable outcome may serve as a basis for patient counselling.