OBJECTIVE To measure the radiation exposure to endoscopists, patients, and assistants during diagnostic and therapeutic ERCP and to assess the effect of a protective lead shield. Radiation dose with and without the protective lead shield was mapped in our standard fluoroscopy room. METHODS Twenty patients undergoing ERCP were selected for this study. Radiation exposure of endoscopists with and without a protective shield was monitored by digital dosimeter. Radiation exposure for diagnostic procedures was correlated with that of therapeutic procedures. RESULTS Endoscopists were exposed to 2.5 mR without the protective shield, but exposure was reduced to an average of 0.27 mR per procedure with the shield. Endoscopists received an average of 1.5 mR per diagnostic ERCP and 3.17 mR per therapeutic ERCP without the shield. When using the protective shield, however, those numbers were reduced to an average of 0.25 mR per diagnostic procedure and 0.28 mR per therapeutic procedure. Radiation exposure to endoscopic assistants, who were not shielded, averaged 0.56 mR per procedure. CONCLUSIONS Amount of radiation exposure to occupational personnel during ERCP was related to duration of fluoroscopy and type of procedure. Radiation exposure to endoscopists can be significantly reduced by the use of a protective shield. Medical assistants received less radiation than did endoscopists because the assistant's position was more distant from x-ray sources.