Abstract Background Patient-reported outcome measures (PROMs) are used by clinical quality registries to assess patients’ perspectives of care outcomes and quality of life. PROMs can be assessed through a self-administered survey or by a third party. Use of mixed mode approaches where PROMs are completed using a single or combination of administration method is emerging. The aim of this study is to identify the most cost-effective efficient approach to collecting PROMs among three modes (telephone, postal service/mail and email) in a population-based clinical quality registry monitoring survivorship after a diagnosis of prostate cancer. This is important to assist the registry in achieving representative PROMs capture using the most cost-effective technique and in developing cost projections for national scale-up. Methods/design This study will adopt an equivalence randomised controlled design. Participants are men diagnosed with and/or treated for prostate cancer (PCa) participating in PCOR-VIC and meet the criteria for 12-month follow-up. Participants will be individually randomized to three independent groups: telephone, mail/postal, or email to complete the 26-item Expanded Prostate Cancer Index Composite (EPIC-26) survey. It is estimated each group will have 229 respondents. We will compare the proportion of completed surveys across the three groups. The economic evaluation will be undertaken from the perspective of the data collection centre and consider all operating costs (personnel, supplies, training, operation and maintenance). Cost data will be captured using an Activity Based Costs method. To estimate the most cost-effective approach, we will calculate incremental cost-effectiveness ratios. A cost projection model will be developed based on most cost-effective approach for nationwide scale-up of the PROMs tool for follow-up of PCa patients in Australia. Discussion This study will identify the most cost-effective approach for collecting PROMs from men with PCa, and enable estimation of costs for national implementation of the PCa PROMs survey. The findings will be of interest to other registries embarking on PROMs data collection. Trial registration ACTRN12615001369516 (Registered on December 16, 2015)