Abstract: Ataxia-telangiectasia (AT) is a rare neurodegenerative disorder characterized by ataxia, telangiectasia, and immunodeficiency. We aimed to evaluate the multisystem involvement in AT by describing clinical features and outcomes of Latin American (LA) patients. cross-sectional and multicenter study. Referral centers from all over LA filled in a questionnaire with clinical and laboratory data based on patients’ records. 228 patients from 10 LA countries were evaluated. Mean ages at the time of symptom onset and diagnosis were 1.63±1.09 and 5.66±3.48 years, respectively. The most common immunodeficiency was IgA deficiency (60.8%), followed by IgG deficiency (28.6%). IgA and IgM showed a tendency to decrease as the patient grew older (p=0.001 and 0.048). IgA deficiency was associated with recurrent airway infections (p=0.038). 120 (79,5%) patients presented with low CD3+CD4+ count and 115 (92%) with low CD19+ count. Regarding nutritional status, as patients grow older there is an increase in severe thinness (p=0.016). Median survival was 23 years and Kaplan-Meier 20-year-survival rate was 52,6%. IgG deficiency and female gender were associated with a decrease in estimated survival function (p=0.02 and 0.049). There is a high prevalence of laboratory immunologic abnormalities and recurrent infections in AT patients. Knowledge of specific regional characteristics and variables which can be related with survival allows for suitable patient follow-up and may increase quality of life Ver menos