This study tried to document the traditional medicinal organisms and their parts used by Tharu ethnic group (hereafter TEG) and we documented a total of 22 animal species including 20 families which they used in treating 25 different ailments among them 68.18% were wild species, 27.27% were domesticated and 4.55% belongs to other, and 103 plant species used in treating 86 different ailments among them 28 species were trees, 13 were shrubs, 51 were herbs and 11 were climber. Most of the animal species used belongs to class mammalian. The study revealed that 51 plants were used for treating of single ailment and remaining 52 species of plants were used for treating more than one ailment. In present exploration we proudly can say that TEG is very much rich from ethnobiological point of view. Data were collected through semi-structured open ended questionnaire survey, direct personal interviews with key informants (faith healers’, they call them, Bharras and Guruwas) and through group discussions. Simple random sampling method was applied for the selection of respondents. The result showed that leaf is highly used in medicinal purposes among all other parts and is successively followed by the root and fruit.