The material of this study composes juvenile skeletons dating to Middle Age from Köşk Höyük in the Bahçeli town of Niğde/Bor district. The study was carried out in order to determine the mortality and morbidity of Köşk Höyük children. Ages were determined by dental calcification, long bone growth, and epiphysis fusion. Diseases have been tried to be diagnosed by macroscopic analysis taking into account the definitions made in the literature. In this work, 118 individuals under the age of 15, including fetuses, were studied. When the 0-15 year olds were considered, the highest death occurred in the first year with 23.8%. When fetuses were included, it was estimated that 21% of those who died in the first year died the first week after birth. This is followed 36-39 weeks of prenatal by 18%. It has been observed that the most important risk factor of children is infectious diseases. It has been thought that its reasons may have been mother and the child nutritional problems. As a result, it can be said that Köşk Höyük children are affected by nutrition problems of mother and child, infectious diseases and cultural practices.

Keywords: child mortality, child morbidity, byzantine period, Köşk Höyük