Background and Purpose: Certain childhood psychological disorders such as autism and attention deficit hyperactivity disorder result in significant psychological damages to parents. Based on the results of different studies, various problems in these children, cause anxiety and stress in their family members. Hence, this study was conducted to compare the coherence and defense mechanisms among the parents of normal children and parents of children with autism and attention deficit hyperactivity disorder. Method: This study was a descriptive and causal-comparative design. The statistical population included all parents of normal children and parents of children with autism and attention deficit hyperactivity disorder in Rasht city in 2016-2017. The sample size of the study consisted of 90 parents who were selected by convenience sampling and based on inclusion and exclusion criteria. Defense Style Questionnaire (Andrews et al., 1993) and Sense of Coherence (Antonovsky, 1987) were used to measure the variables. The data were analyzed by multivariate analysis of variance. Results: The results of the study indicated that there was a significant difference among the three groups of parents of normal children and parents of children with autism and attention deficit hyperactivity disorder in each component of coherence (p<0.05). Parents of children with attention deficit hyperactivity disorder had the lowest mean score in coherence (90.96), while the highest score (101.93) was for the group of parents with normal children. There was a significant difference between the three groups of parents in each component of defense mechanism (p<0.05). Conclusion: Based on the results of the current research, parents of normal children and parents of children with autism and attention deficit hyperactivity disorder experience higher levels of mental stresses related to parenting, which may be caused by the special needs of these children and the distinctive psychological and mental differences between them and their peers. In this way, planning and implementing appropriate psychological and educational interventions for the parents of these children, with an emphasis on the initial interventions, can be very helpful.