Purpose:To study the lymphatic drainage of the cynomolgus monkey and human eyelid and periocular tissue by means of histochemistry.Methods:Eyelid and periocular tissue from three cynomolgus monkeys undergoing sacrifice for glaucoma and retina research purposes and discarded tissue from a wedge resection of one human eyelid were used for histochemical analysis. Lymphatic capillaries were distinguished histochemically in monkey and human eyelids by light microscopy with a 5′-nucleotidase (5′-Nase) staining method. Identification of lymphatic vessels was based on strict morphologic criteria combined with specific 5′-Nase staining.Results:Histochemical analysis with 5′-nucleotidase revealed a subcutaneous and pretarsal lymphatic plexus in both the human and monkey.Conclusions:Histochemical results demonstrate similar lymphatic plexi in the monkey and human. Future studies will help to clarify the lymphatic drainage pathways of monkey and human eyelids.