Mosaic Trisomy 22 with minimal physical findings and normal development are under diagnosed we report here a case of mosaic trisomy 22 i.e. 46, XX/47, XX, +22 in a girl aged 16 years. Most of the time trisomy 22 is seen in abortus material, In contrast live birth of MT22 is rarely seen due to severe organ malformations and bone deformities were visible after age of 1 year. The boney deformities included swelling in feet, rigidity in hands and legs. The patient also had congenital heart disease (Atrial Septal Defect).Cytogenetic analysis was carried out on peripheral blood lymphocytes, twenty metaphases were analyzed and revealed with mosaic trisomy of chromosome 22. The severity of the disorder can depend on the number of cells in which the extra chromosome 22 is present.