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Background and Objective: Low birth weight (LBW) is one of the most important problems in the world. Many morbidity are more prevalent in LBW included in attention deficit and hyper activity disorder (ADHD). This study was done to find the Relation between low birth weight with attention deficit and hyper activity disorder in children. Methods: This historical cohort study was done on 226 rural children in Yazd province, central area of Iran. ADHD symptoms were evaluated in LBW and NBW using DSM-IV criteria. Results: Frequency of ADHD was 22.8% in LBW and 12.5% in NBW (P<0.05). The mean of family members was 4.7±0.6 and 4.2±0.8 in child with ADHD versus child without ADHD (P<0.05). Odd's ratio for ADHD was 3.1 in patient with more than one sister or brother (95% CI: 1.2-7.9, P<0.001), and 5.7 in patients with positive familial history (95% CI: 2.6-12.4, P<0.001). Conclusion: Relationship between ADHD and LBW was statistically significant. Positive familial history for ADHD and over-crowded family were social factors related with ADHD. LBW is one of the risk factors for ADHD and can be considered in children health program ADHD was frequent in child with low birth weight than child with normal birth weight.