Abstract:Autism Spectrum Disorder (ASD) is an important developmental disorder worldwide with a prevalence of 0.09% - 1.07%, in the Southeast Asia population including India.Objectives: The primary objective of the study was criterion validation of ‘ASD-related items’ in NDST as a screening tool for ASD against AIIMS-modified INDT-ASD as gold standard and to calculate sensitivity, specificity, predictive values, diagnostic accuracy, and likelihood ratios. Methodology: This is a descriptive study - diagnostic test evaluation, which was carried out from January- July 2022, at NIMS Spectrum - CDRC, Thiruvananthapuram, a tertiary care center for children with neurodevelopmental problems. Fifty children, who came to CDRC with suspected developmental problems were screened with ASD-related items in NDST by an experienced Developmental therapist and