Purpose: We estimated the risk of a rapid prostate specific antigen (PSA) increase in men with a low baseline PSA range of 0.0 to 2.0 ng/ml to investigate the validity of setting a re-screening interval of more than 1 year. Materials and Methods: Between 1988 and 1999, 6,252 men with baseline PSA 2.0 ng/ml or less without suspicious findings on digital rectal examination (DRE) and 7,304 with the same baseline PSA who did not undergo DRE at the time of baseline PSA measurement were rescreened. The risks of a PSA increase to 4.1 to 10.0, 10.1 to 20.0 and greater than 20.0 ng/ml were investigated and stratified by re-screening interval, baseline DRE status, and subdivided baseline PSA ranges of 0.0 to 1.0 and 1.1 to 2.0 ng/ml. Results: A total of 28 cases (0.2% of 13,556) of prostate cancer were detected after an average re-screening interval of 3.6 years. High PSA above 10 ng/ml at diagnosis was noted in 5 patients (18%), including 2 with a great PSA increase to 1,928 and 298 ng/ml at re-screening intervals of 4 and 6 years, respectively. Conclusions: Setting 4 to 5-year re-screening intervals for PSA measurements in men with PSA 1.0 ng/ml. or less can decrease the cost of PSA tests without lowering sensitivity. A re-screening interval for PSA measurement should be set annually for men with PSA 1.1 to 2.0 ng/ml to minimize the risk of missing aggressive cancer.