Abstract : Blood donor selection is important to ensure the safety of both donors and recipients. Blood safety a major issue in the field of transfusion medicine. Persons who are disqualified or rejected from donating the blood are known as deferred donors.it is well known that a large number of apparently healthy donors are deferred from successful blood donation because of varied reason. They are the potential motivated donors the society losing. Hence it is very important to evaluate the reasons for deferral and retain the motivated donors. To evaluate the reasons of predonation deferral Source of data All the donors screened for blood donation in the blood bank and blood camps at SIMS, Shivamogga. Study type Retrospective study. Study period January 2017 to December 2018 Study duration Two year. Sample size 16,286 cases. Plan of data analysis Descriptive statistics will be done using Microsoft excel. It is a retrospective study. Causes of donor deferral were evaluated respectively including both in hospital donation (and outdoor camp donation) including voluntary and replacement donors from January 2017-december 2018 in Shimoga institute of medical sciences, Shivamogga. Karnataka. Among 16,286 donors screened, 1229 (7.54 %) were deferred from blood donation. temporary deferrals were significantly higher than permanent deferral. The most common reasons for temporary deferrals were anaemia (32.3 %), followed by underweight (20.17 %), medication (12.12 %), high BP (11.06 %). The common causes for permanent deferral included being uncontrolled BP followed by diabetes, heart disease, Hep B surface antigen and epilepsy. Insight into the reasons of donor deferral is very important to avoid the permanent loss of the donor as blood donation program is the life force behind any blood bank or hospital. deferral study also indicates the health status of the general population. Since most of the deferrals are temporary deferrals and we should give a clear message for the reason for deferral, so that they return for donation in the future.