This article describes the ultrasonographic findings of the reticulum, rumen, omasum, abomasum, and liver of calves from birth to 100 days of age. Reticular motility is used to exemplify how the forestomach function in calves progresses and gradually approaches that of adult cattle. The ultrasonographic examination of the esophageal groove reflex and the investigation of factors affecting esophageal groove closure are described. The ultrasonographic findings of the forestomachs and abomasum of calves with ruminal drinker syndrome are discussed. The article concludes with the description of the ultrasonographic examination of the liver.