Abstract Objectives To demonstrate the production of the local toxocara antibodies in the vitreous of patients with negative serology. Material and methods Retrospective review of the medical records of patients seen in a Tertiary Referral Hospital, and at an Eye Institute, with an ocular diagnosis of toxocariasis who had a negative serology and positive titers in the vitreous. Results After reviewing the medical records of 40 patients with a diagnosis of ocular toxocariasis, a total of six cases (15%) were found with a negative serology and a positive vitreous titer for toxocara antibody, both of them performed using an ELISA procedure. The mean age was 18 years, there were no differences observed between males and females. A peripheral granuloma was the most common clinic finding, and all patients underwent vitrectomy either to remove epiretinal membranes or to repair retinal detachments. Conclusion A negative serology does not rule out a diagnosis of ocular toxocariasis. Vitreous samples may be necessary to confirm a clinical diagnosis.