Objective: In this report, we aim to increase the aware ness of mosaic trisomy 8 syndrome, by presenting clinical features of 5 patients and accompanying structural malformations. Material and Methods: Patients who applied to pediatric genetic department between 2000-2022, and were found to have trisomy 8 mosaicism as a result of karyotype analysis performed from peripheral blood samples were in cluded in the study. Results: Of all 5 patients, 2 were male, 3 were fe male. The age at the admission ranged from 11 months to 9 years. Fetal karyotype analysis was recommended to the families of 3 patients who were found to have at least one of the findings of abnormal fetal screen ing test, corpus callosum agenesis, hydrocephaly or urinary sistem ab normality in the prenatal period, but one family agreed to sampling. Karyotype analysis from amnion sample was performed to the patient and resulted in normal. In the postnatal evaluation, 3 patients had cen tral nervous system abnormality, 4 patients had heart defect and 3 pa tients had urogenital system abnormality and all patients had at least one musculoskeletal system abnormality. Deep palmar-plantar creases, which is one of the hallmark of the syndrome was present in 4 patients, camptodactyly and strabismus were detected in 4 and 1 patients, re spectively. Developmental tests of all patients were abnormal. Con clusion: Mosaic trisomy 8 syndrome is a clinically heterogenous syndrome and it should be considered in the differential diagnosis in the presence of the developmental delay, corpus callosum agenesis, camp todactyly and deep palmar-plantar creases.