Phenylketonuria and congenital hypothyroidism are the inherited metabolic diseases that can be diagnosed and successfully treated early from birth. Nevertheless, children with phenylketonuria and congenital hypothyroidism are found to be in the risk for psychological maladjustment. Parental adjustment - as significant condition for child's psychological adjustment--and related factors are explored in this study. Parents of 63 children with congenital hypothyroidism and phenylketonuria (age 2 to 14 years) answered the Child Behavior Checklist, Coping Strategies Questionnaire and the questionnaire on reactions to child's disease, relations with a sick child, with the spouse and other people. Severity of the disease and child's age are considered as well. Results of the study show that parental emotional (maladaptive) coping and indulgence of a sick child account for the higher rates of internalizing problems of children with phenylketonuria and congenital hypothyroidism. In addition, the higher rates of children's psychological problems are related to parental feelings of guilt as a reaction to child's disease.