There are several unique features in the anatomy of the stomach in African ostrich in comparison with other birds. The goal of this study was to determine changes in the main morphometric parameters and histological features of gastric mucosa in ostrich chickens from the 38th day of embryonal development until 60 days of age. For the study, 6 embryos (38th day of development) and 36 chicks (1, 3, 7, 14, 30, and 60 days post hatching; 6 chicks per time point) of both sexes were obtained from African ostrich farm in Latvia during May - October, 2009. Tissue samples were investigated in Preclinical Department, Faculty of Veterinary Medicine. The total area of proventricular mucosa (cm2) and surface area of deep glands (cm2) was measured. Tissue sections for histological assessment were stained with: hematoxylin and eosin and alcian-blue pH 2.5 - periodic acid – Schiff reaction. Thickness of proventricular and ventricular mucosa, depth of proventricular superficial glands as well as surface area of parenchyma occupied by deep glands were measured in histologic sections. As the chick age increased, there were changes in the ratio of areas occupied by proventricular superficial and deep glands with relative decrease in area occupied by deep glands. Proventricular deep glands developed rapidly after hatching; at the age of 30 days deep glands histologically resembled glandular structure of adult birds. Gastric mucosal epithelial cells of 38 days old ostrich embryos and of just hatched ostrich chicks contained neutral, acidic, and mixed mucopolysaccharides. Meanwhile, in the pyloric region of ventriculus acidic mucopolysaccharides predominated.