The current debate regarding early detection and aggressive treatment of prostate cancer is fueled by the absence of controlled studies defining the risks and benefits of prostate cancer screening, and by the lack of adequately powered trials demonstrating the benefit of curative treatment for early-stage prostate cancer. Pending the results of clinical trials in 10 to 15 years, advocates of early detection of prostate cancer with digital rectal examination and prostate-specific antigen have compared prostate cancer screening with the effective strategy of breast cancer screening, implying that prostate cancer screening should similarly reduce cancer mortality. They have also cited the high burden of disease, the acceptable operating characteristics of digital rectal examination and prostate-specific antigen, a stage shift among cases detected by screening, and the theoretical curability of early-stage disease as sufficient reasons to proceed with screening. These arguments, however, are reminiscent of earlier arguments in favor of lung cancer screening with chest x-ray examination and sputum cytology, a practice ultimately proven ineffective in clinical trials. We reviewed published articles on lung and prostate cancer screening and identified many parallels. While prostate cancer screening may one day prove effective, analogies between the current prostate cancer screening controversy and the older lung cancer screening debate should inject some caution regarding widespread dissemination of prostate cancer screening without experimental evidence that such screening does more good than harm.