HIV screening of all donated blood is mandatory in India. The program instituted has many inherent lacunac like arbitrary identification of centres, absence of a guardian quality control program, criterion for test kit selection and absence of standard guidelines. This study was undertaken to evaluate the effects of frequent change of testing laboratory, change of testing staff, change of reagent kits and time of blood donation. All the donations at blood bank Safdarjang Hospital, during the year 1993, were taken for study. HBsAg and VDRL positivity were used as control/check value for similarity of donor population. Tests done during this period in three different laboratories show that the change of laboratory, change of reagent kit and the experience and training of the testing laboratory staff affect the test results, causing an increase in the number of false positive tests. This leads to destruction of donated blood which would have been otherwise fit for transfusion. It is suggested that a proper policy plan may be made and implemented in order to make the blood screening more effective.