Concerning functional and morphological aspects, the ovary of the cynomolgus macaque is representative for the conditions in higher primates like humans and is therefore of major relevance in toxicological research. Against this background, a comprehensive overview about the cynomolgus macaque ovary is given from its embryonic appearance, throughout the adolescent and adult development until old age. The overview includes morphologic characteristics, a description of the different cell types, comparisons between the expression of selected receptors, and some details on hormonal effects if considered necessary for understanding the unit of ovarian morphology and function. The close correlation of hormones and morphological characteristics of the ovary and of the other reproductive organs is emphasized by several schematic drawings and images. Special emphasis is also laid on the comparison to the human organism indicating the similarity of both species and hence underlining the importance of the cynomolgus macaque as a model in toxicological research.