Twenty apparently healthy layer chickens at different ages were divided into four groups according to age with five chickens each: Group 1, 10-12 weeks; Group 2, 18-20 weeks; Group 3, 28-30 weeks; and Group 4, over 50 weeks. An ultrasound machine equipped with a 5.0 MHz linear array scanner was used to examine the heart, liver, gallbladder, spleen, ventriculus and proventriculus. After ultrasound examination, each chicken was sacrificed by cervical dislocation. The organs were then examined and measured grossly. The heart appeared as a rapidly contracting anechoic structure. The spleen and liver had hypoechoic parenchyma. The gallbladder and proventriculus had hypoechoic walls with anechoic lumen while the ventriculus had hyperechoic walls with hypoechoic or anechoic lumen. Both ultrasound and gross measurements of liver thickness in 18-20 week-old layers were significantly lower than the other age groups. No significant differences in both gross and ultrasound measurements of the diameter of spleen and gall bladder were observed among the four age groups. The mean diameter of the proventriculus and ventriculus in 28-30 week-old layers as measured grossly was significantly higher than the other age groups. The results of the study could be used for determination of abnormalities of the different organs in layer chickens.