"Mental Retardation" is a disorder in which a person's overall intellectual functioning is well below average. Individuals with Mental Retardation have a significantly impaired ability to cope with common life demands and lack some daily living skills expected of people in their age group. There are four degrees of severity of M.R. based on IQ score: mild, moderate, severe, profound. CONCLUDING REMARKS 1. Children spontaneously use metaphors in the symbolic games and in the process of learning language in which objects are often called whit names of other things. We didn't find this in mental retardation. 2. Without explanation idiom and non literal use of a word can't be easily understood. 3. People with mental retardation can understand sentences that children are not able to understand because they have an amount of experience that is superior of that of a child. 4. Figurative expressions related with body experience are comprehended more than others. (Donella Antelmi and Adriana Morlacchi)