Purple yam (Dioscorea alata L.) is a source nutritious tubers that has not been used optimally. Nutrients content in Dioscorea species are starch, essentials amino acid, minerals, polyphenol, glycoprotein, purin derivates such as allantoin, and steroid saponin which have biological activity such as immunomodulatory and antiallergic. The purpose of this research was to assess the absolute number of lymphocyte on hypersensitivity of mice after treated with ethanol extract of D. alata. Twenty one male Balb/C mice were used which were divided into seven groups: control (C), negative control (NC), treatments with ethanol extract of D. alata 0.17 g/kg, 2.01 g/kg, 10.04 g/kg (T I – T III), treatment with antihistamine drug 0,4 mg/mice/day (T IV) and treatment with diosgenin 200 mg/kg (T V). For 17 consecutive days the T I - T III groups were treated with ethanol extract of D. alata correspond to their doses, T IV group were treated with antihistamine drugs, and T V group were treated with diosgenin. On day 15, NC and T I – T V groups of mice were induced by ovalbumin 0,0483 mg/mice. Mice were sacrificed on day 18, and the lymphocyte was isolated from spleen, and the absolute number of lymphocyte was counted with Haemocytometer. Results showed that the absolute number of lymphocyte on mice hypersensitivity after treated with ethanol extract of D. alata L. were the lowest, while the highest absolute number of lymphocyte was found in the group treated with antihistamine drugs followed by the group treated with diosgenin on 200 mg/kg BW, negative control group and control group, respectively.