Objective: The aim of this study was to investigate chromosomal abnormalities among mentally retarded children attending special classes at Antalya Guide and Research Center (MEBARAM).Methods: One hundred and fifty-one children having different IQ and ages attending special classes of MEBARAM were screened for chromosomal abnormalities using cytogenetic techniques.Results: The significant chromosomal abnormalities have been found as both major (3.97%) and heteromorphic (11.25%). The major chromosomal abnormalities were 46,Y, fra(X) (q27.3), 46,X, fra(X) (q27.3) with fra (3) (p14) and fra(16) (q23), 46,Y, fra(X) (p22), 46,XY, fra(8) (q22), and two cases 47.XX+21. Seventeen out of 151 children had different types of heterochromatic chromosomal abnormalities (1qh+, 10qh+, 15ph+, 16qh+, 21ph+, 22pss, Yqh+, Yqh-) and two had pericentric inversion of chromosome 9.Conclusion: We suggest that children with learning difficulties should be screened for chromosomal abnormalities. Families with incidences of a child having fra (x) (q 27.3) and trisomy 21 chromosomal abnormalities should be quided towards prenatal diagnosis with genetic counseling.