First-degree relatives (FDRs) of prostate cancer patients are known to be at increased risk for the disease, yet relatively little is known about their screening behaviors. The current lack of consensus about the value of prostate cancer screening underscores the importance of examining why some men at increased risk participate in screening and others do not. In this study, variables from Protection Motivation Theory were used to identify predictors of prostate specific antigen (PSA) testing in this at-risk population. Toward this end, scales assessing perceived vulnerability, perceived severity, response efficacy, and self-efficacy for prostate cancer screening were administered to 82 unaffected male FDRs aged 40 and older. When recontacted approximately 14 months later, 50% of FDRs were found to have undergone PSA testing in the interim. Older age, prior prostate cancer screening, and a greater sense of personal efficacy about being able to undergo prostate cancer screening were found to be significant (P < 0.05) predictors of subsequently undergoing PSA testing. These findings provide partial support for the predictive validity of Protection Motivation Theory variables and suggest the importance of considering efficacy beliefs in attempting to understand decision-making about PSA testing in at-risk individuals.