The aim of this study is to evaluate and compare the performance of two dose calibrators which are used in Nuclear Medicine Center by standard tests accuracy, constancy, linearity and geometry. To check the performance status of the dose calibrators the activity of radiopharmaceuticals must be accurately known before administered to the patients. Two dose calibrators of Institute Nuclear Medicine and Allied Sciences, Dhaka (Capintec, Inc.,Model no. CRC 25R and Veenstra , model no. VDC 404) performances were compared in accordance with varying geometry because most common measurement geometries utilized in clinical practice are glass vials, solid capsules and various types of plastic syringes. Vials and syringes filling volumes can be widely different, according to clinical needs. It was found that the measurement activity readings of one of these two dose calibrator, VDC-404, showed slightly deviating from accurate value because readings might be affected by the frequent change in background count. The results of the quality control (QC) tests revealed that the parameters that were traced for both dose calibrators were within the limits of the international standards, ?5%. Regular QC should cover precision, accuracy, linearity, and geometry of instrument, according to IAEA standards, e.g. (IAEA TECDOC-602 and 1599), that will guarantee to assure the proper practice of nuclear medicine diagnosis. It is also vital to fulfill radiation protection requirements as well as successful therapies and good quality image production in nuclear medicine practices.