This chapter has cover classification of allergens, hormone allergens and different hormones. 10 well illustrated pictures and diagrams are included to show structure of hormones, site of different glands, metabolism of hormones and their blood levels in male and female. Hormone allergy, hormone allergens, atopy, allergen, plant foods, aminal foods, synthetic foods, contactants, inhalants, drug allergens, intrinsic allergens, cortisol, adrenaline and sex hormones are described in detail. 19 references are given at the end of the chapter for further reading. References are mentioned in text at appropriate places for the benefit of readers.