Objective: Radical prostatectomy (RP) and radiation therapy are standard curative approaches for low-risk prostate cancer (PC). Active surveillance (AS) is becoming an increasingly accepted management alternative for low-risk PC. Our aim is to compare the cumulative medical costs of treatment vs. AS., Methods and Materials: We collected data on the cumulative medical costs of open radical retropubic prostatectomy (RRP), robotic-assisted radical prostatectomy (RARP), external beam radiotherapy (EBRT), brachytherapy (BT), and AS at our institution. For physicians' reimbursements, Medicare values of our region were used to maintain uniformity. For inpatient costs other than reimbursements, we used the mean cost at our institution. The costs of RRP and RARP involve preoperative investigations, medical clearance, physicians' fees, inpatient costs, and pathologic examination of prostatectomy specimen and follow-up. The inpatient costs include the operating room, disposable equipment, anesthesia, post-anesthesia care, transfusion, and hospital stay. The cost of EBRT involves the cost of consultation, planning, simulation and treatment sessions, and follow-up. BT costs involved radiotherapy planning as well as inpatients costs. AS protocol involves regular visits, transrectal ultrasound guided biopsies, prostate specific antigen (PSA) testing. To evaluate the cost of treating complications, treatment after AS, and treatment for recurrence, we created a Markov model based on recent studies and our experience., Results: The cumulative costs of RRP are $9,732 (1 year), $10,360 (2 years), $12,209 (5 years), and $15,084 (10 years). While for RARP, the costs are $17,824 (1 year), $18,308 (2 years), $20,117 (5 years), and $22,762 (10 years). The costs of EBRT are $20,730 (1 year), $20,969 (2 years), $22,043 (5 years), and $23,953 (10 years). BT costs are $14,061 (1 year), $14,300 (2 years), $15,374 (5 years), and $17,284 (10 years). The costs of AS are $1,154 (1 year), $2,308 (2 years), $8,761 (5 years), and $13,116 (10 years)., Conclusions: The cumulative medical costs of RARP and EBRT are much higher than BT, RRP, and AS. AS is associated with a different cost distribution in which the initial cost is low and relatively higher cost of follow-up. Despite the higher follow-up cost, AS remains the most cost effective alternative for low-risk PC., (Copyright © 2013 Elsevier Inc. All rights reserved.)