Purpose: To estimate the risk of cataract in a cohort of nuclearmedicine (NM) radiologic technologists on the basis of their work histories and radiation protection practices.Materials and In the years 2003—2005 and 2012—2013, 42 545 radio- Methods: logic technologists from a U.S. prospective study com-pleted questionnaires in which they provided information regarding their work histories and cataract histories. Cox proportional hazards models, stratified according to birth- year cohort (born before 1940 or born in 1940 or later) and adjusted for age, sex, and race, were used to estimate hazard ratios (HRs) for the risk of cataract in radiologic technologists according to NM work history practices ac- cording to decade.Results: During the follow-up period (mean follow-up, 7% years),7137 incident cataracts were reported. A significantly in- creased risk of cataract (HR, 1.08; 95% confidence interval [CI]: 1.03, 1.14) was observed among workers who performed an NM procedure at least once—as opposed to never. Risks of cataract were increased in the group who had performed a diagnostic (HR, 1.07; 95% CI: 1.01, 1.12) or therapeutic (HR, 1.10; 95% CI: 1.04, 1.17) NM procedure. Risks were higher for those who had first performed diagnostic NM procedures in the 1980s to early 2000s (HR, 1.30; 95% CI: 1.08, 1.58) and those who had performed therapeutic NM procedures in the 1970s (HR, 1.11; 95% CI: 1.01, 1.23) and in the 1980s to early 2000s (HR, 1.14; 95% CI: 1.02, 1.29). With the exception of a significantly increased risk associated with performing therapeutic NM procedures without shielding the radiation source in the 1980s (HR, 1.32; 95% CI: 1.04, 1.67), analyses revealed no association between cataract risk and specific radiation protection technique used.Conclusion: An increased risk of cataract was observed among U.S.radiologic technologists who had performed an NM procedure at least once. This association should be examined in future studies incorporating estimated lens doses.