INTRODUCTION: The administration of the National Screening Test (PruebaNacional de Pesquisa, PRUNAPE), a tool which is effective to screen inapparent developmental disorders in children under 6 years old, requires adequate training, time, space and furniture. A simple questionnaire to help screen large population groups could be useful to identify children at risk. OBJECTIVE: To evaluate the validity of the PRUNAPE pre-screening questionnaire (cuestionario PRUNAPE pre-pesquisa, CPPP) to identify children at risk of not passing the test. METHODS: Fifty seven PRUNAPE milestones were transformed into questions; they were organized in fve questionnaires (one for each age group between 6 and 71 months old) with illustrative pictures. The study was performed in Florencio Varela and in the Health Promotion Unit of Hospital de Niños "Ricardo Gutiérrez" in the Autonomous City of Buenos Aires. In a sample of 533 healthy children and their mothers, of a low socio-economic level, the CPPP was consecutively: a) self-administered by each mother (CPPP-SA), b) by healthcare personnel (CPPP-HP), and fnally, c) the PRUNAPE test was administered to each child by qualifed professionals. Each step was performed by a different professional in a triple-blind fashion. When choosing the cutoff point, the positive predictive value (PPV) was prioritized to reach the least possible number of false positives. RESULTS: For the CPPP-SA and the CPPP-HP, the overall results were, respectively: Cohen's kappa coeffcient: 0.23 and 0.28; sensitivity: 0.41 and 0.42; specifcity: 0.81 and 0.85; negative predictive value 0.57 and 0.59; and PPV 0.71 and 0.76. CONCLUSIONS: The CPPP is a valid tool to identify children who most require the PRUNAPE to be administered.