Background The developmental delays of children, is one of the most important sources of information to detect the developmental delays of children. The aim of this study was to investigate the developmental delays and its relationship with anthropometric indices in Urmia city, Iran. Materials and Methods This is a descriptive analytical study that conducted on 422 children who had 6-12 months old and were selected randomly with cluster sampling from 10 Health Center. Anthropometric indices (weight, height and head circumstance) were collected from recorded files, and development of children was measured using developmental test of Ages and Stages Questionnaires (ASQ). The data were analyzed using SPSS version 18.0 software. Results The results showed that the prevalence of the developmental delays of children was 18.8% and the highest and the lowest prevalence was related to the area of communication (7.1 %), and the area of gross motor (0.9 %), respectively. The developmental delays of children in boys, was more than girls (P 0.05). Conclusion Considering the significant number of the developmental delays of children and its relationship with birth weight in this study, it is recommended to consider appropriate interventions at pregnancy period for the prevention of low birth weight and the constant programs about the developmental delays