Objective: The purpose of present research was the comparison of mothers irrational believes with severe or profound mentally handicapped child and mothers with normal child from 6 to14 years old in Tehran city.

Materials & Methods: This study was an analytical, cross – sectional and comparative (case – control) research. From mothers with severe or profound mentally handicapped child who had refered to Tehran welfare services centers, 80 mothers were selected by regular randomized sampling from two rehabilitation centers and 80 mothers with normal child were selected for peering with the group of testimonial from schools areas of east, west, south, north and center of Tehran, through multi - stage cluster sampling in for variables of: age of mothers, educational levels, the location of living and the number of children. They answered to questionnaire of irrational believes of jons (IBT). Analysis of data was done by descriptive and infringing statistics methods (Independent T test, U Mann Whitney, Chi-square and fisher).

Results: The findings showed that: there are significantly differences in total irrational believes and irrational believes of blame proneness, frustration reactive, anxious over concern, problem avoiding and dependency, perfectionism between two groups of mothers (P<0/05). There was no significant difference in irrational believes between mothers who had mental handicap daughter and mothers who had mental handicap son (P=0/314). There was no significantly difference between two groups of mothers in four believes of demand for approval (P=0/737), high-self expectation (P=0/126), emotional irresponsibility (P=0/727), helplessness for change (p=0/283).

Conclusion: Irrational believes and many its sub scales. In mothers of severe or profound mental handicap children were more than mothers with normal child. But believes of demand for approval, high self expectation, emotional irresponsibility, helplessness for change in mothers with handicap child was not more than mothers with normal child. Also sexuality of handicap child doesn't effect in mothers irrational believes.