Background Children that living with addicted parents are at risk for intentionally and unintentionally poisoning. Present study aimed to evaluate the effect of parental addiction on unintentional childhood poisoning. Materials and Methods: Totally, 140 admitted children with poisoning in Loghman hospital, Tehran-Iran, as referral center were recruited from March 2013 to July 2014. Cases were matched with 280 controls by age (within a caliper of six months), gender, and date of hospital attendance in Tehran, Iran. Parents were interviewed using an objective checklist about the risk factors of childhood poisoning. Conditional logistic regression with within-group varying weights was used to adjust for measured confounders. Vary weights within the matched set was defined by inverse probability weighting (IPW). Results: Sixty-two of cases (74.7%) were poisoned with Methadone. The odds ratio [OR] 95% confidence interval [CI] of having addicted parents in poisoned children compared to the controls in three scenarios of ordinary, un-stabilized weighted and stabilized weighted conditional regression logistic ORs (95% CI) were 17.3 (8.7, 34.6), 2.6 (1.9, 3.3) and 3.6 (2.9, 4.3) respectively. Conclusion The results indicate that child abuse and neglect have been linked to parental substance abuse. Education on preventive interventions such as safe storage of methadone and store poisoning product out of reach and sight of children are necessary in substance abusing families.