This study was conducted in order to assess normal liver, spleen and kidney dimensions in premature and term newborns and determine the acceptable range. A total of 253 (99 preterm and 154 term) healthy newborns were evaluated within the first week of life by sonography. Gestational age ranged from 24 to 41 weeks, weight ranged from 638 to 4800 g. Measurements were compared with gestational age, weight and height of the infants. Normal ranges for kidney, liver and spleen measurements according to gestational age and weight were obtained. We found that weight showed the best correlation with any one of the mentioned organ dimensions.