This study evaluated the feasibility of determining effective renal plasma flow (ERPF) at an off-site central laboratory by transferring blood samples from the on-site laboratory. METHODS Blood samples were obtained from 66 patients referred for renal imaging with 99mTc-MAG3. ERPF values were determined using the single blood sample method (BSM) at both on- and off-site laboratories. The ERPF values were classified clinically as normal or abnormal. Both the ERPF values and clinical classification were compared between on- and off-site laboratories. RESULTS The off-site ERPF overestimated those on-site by 2.8% (paired Student's t-test p < 10(-5)). However, off-site ERPF values highly correlated with the values obtained on-site (r = 0.99; p < 10(-5)). In addition, the clinical classification for each patient determined at each site was identical. CONCLUSIONS ERPF can be determined accurately off-site. This method should allow many nuclear medicine departments access to the ERPF determination by the BSM at a central off-site laboratory.