Objective: to analyze the validity of self-reported somatometry data through a self-reported online questionnaire. Method: the SENDO project (Follow-up of Children for Optimal Development) is a prospective, dynamic pediatric cohort. Participants are recruited when they are between 4 and 6 years old, and followed annually through an online questionnaire. In a subsample of 82 participants, we compared the anthropometric information reported in the baseline questionnaire with the direct measurements collected by the investigating staff. To do this, we calculated the intraclass correlation index (ICC) and the Bland-Altman coefficient. Results: the ICC was 0.96 (95 % confidence interval [CI]: 0.94-0.98 for weight; 0.95 (95 % CI: 0.92-0.96) for height; 0.75 (95 % CI: 0.64-0.86) for waist circumference; and 0.84 (95 % CI: 0.76-0.89) for hip circumference. In relation to the indices calculated from these measurements, we found an ICC of 0.84 (95 % CI: 0.77-0.90) for body mass index; 0.46 (95 % CI: 0.27-0.62) for waist-hip ratio; and 0.59 (95 % CI: 0.43-0.72) for waist-height index. The Bland-Altman index ranged from 3.7 % for weight to 8.5 % for body mass index. Conclusions: we found a high correlation and concordance between the data collected in the physical exam and those reported by the parents. Our results indicate that the anthropometric measures provided by parents, especially those with which they are most familiar, are valid and can be used in epidemiological research.