Screening and surveillance of prostate cancer typically involves sensitive laboratory techniques for the quantification of plasma prostate specific antigen (PSA). In this study, we determine the sensitivity and specificity of a simple test strip based PSA assay using only a few drops of whole blood as compared to a standard plasma PSA assay. Blood samples will be taken from hundred patients who are followed for a prostatic disease needing PSA surveillance. Before decantation of the samples, a few drops of blood will serve for the rapid test on strips. Plasma PSA levels will be determined with the TRACE ("Time Resolved Amplified Cryptate Emission") technology in homogeneous liquid phase. The results from the rapid test can then be compared to the plasma levels obtained by TRACE.