Objective: Incorporate the immune function as determined by the absolute lymphocyte count (ALC) into the CAPRA-S risk stratification score to determine if predictive values could be improved. Materials and Methods: The clinical pathological findings in the surgical specimen and total PSA were used to define the three CAPRA-S risk groups. One month after surgery and at each follow up total PSA and the ALC were determined, until biochemical failure (BF) or the end of the study period. A cut off value of < 1,000 lymphocytes/mm3 was used to define lymphocytopenia (LCP). Each CAPRA-S group was sub-divided based on the presence or absence of LCP. Kaplan-Meier biochemical failure free survival (BFFS) curves and restricted mean biochemical failure free survival times were calculated for each group. Results: 404 patients participated of whom 103 (25.5%) underwent BF. 270 men were CAPRA-S low risk (LR), 89 intermediate risk (IR) and 45 high risk (HR), of whom LCP was found in 22 (8%) of low risk, 24 (27%) of intermediate risk and 17 (38%) of high risk men. LCP was significantly associated with a higher PSA, higher Gleason and CAPRA-S scores and BF. HRs were 1.76 for IR, 2.49 for HR and 1.29 for LCP. Five-year BFFS for men without LCP, LR 93.5%, IR 61% and HR 36%, for those with LCP, LR 55%, IR 25% and HR 6%. All patients with LCP and IR or HR scores relapsed within 6 years. 10 year BFFS for men without LCP were 71% LR, 43% IR and 23% HR, LR with LCP 16%. Men with BF had increasing LCP approximately 18 months before BF. Conclusions: The incorporation of the ALC taken one month after surgery with the CAPRA-S improves risk stratification; decreases in the ALC suggest that BF is occuring. These results need to be confirmed with larger studies.