This study investigates the occupational radiation dose to interventional radiologists and the operator-controlled factors that may affect dose. Thirty interventional radiologists wore radiation badges over and under lead aprons for 2 months and answered a questionnaire. The relationships between dose and caseload, case mix, experience, optional fluoroscopy features, lead apron type, and additional lead shielding were evaluated. Mean projected yearly dose (PYD) over lead was 49.1 mSv (1 mSv = 100 mrem) but was 66.6 mSv for persons performing 1,000 or more cases per year (P = .027). Mean PYD under lead was 0.9 mSv but was 1.3 mSv for persons with 0.5-mm lead coverage and 0.4 mSv for those with 1.0-mm lead coverage (P = .002). No other significant correlation was found. Conclusions are that caseload and apron thickness are the primary determinants of total body dose, that over-lead dose is high enough to warrant additional lead shielding for the head and neck, and that a double-thickness apron lowers under-lead dose by two-thirds. The large difference between under-lead and over-lead doses suggests that use of a collar badge alone for monitoring purposes is not predictive of total-body effective dose for this group of radiation workers.