Objective: to achieve factors probably causing to born exceptional children in families who have more than one exceptional children.

Materials & Methods: In this cross sectional and comparative study 80 family who have more than one exceptional children were selected conveniently and 53 family with normal children were selected by multi-stage sampling via schools of city of Urmia. In this study the biological characteristics of questionnaire - the cognitive parents with more than one child special and general health questionnaire was used. Analysis of data compromise Xi Chi, Yu-Whitney and t tests were used.

Results: Among demographic variables, sequence of children birth (P<0.001), disease (P=0.006), type of disability (P=0.001) and Major cause of handicap (P=0.014) were significant between two groups. Among biological variables, type of marriage (P=0.019), parental age at marriage (P<0.001), mother’s age during pregnancy (P=0.031), birthplace of parents (P<0.001), mother’s general health (P=0.012) and parent’s blood group (P<0.001) were significant between two groups.

Conclusion: Prevention and planning to control variables affecting the birth rate of Exceptional Children in families that have been investigated in this study will help to reduce disabilities.