Objectives: During the PRO linguistic validation process, harmonisation is vital; it ensures conceptual equivalence of the translations, allowing trial data to be compared across cultures. The 2005 ISPOR Taskforce Report outlined two methods for achieving harmonisation: a formal meeting with translators from each target language and the instrument developer, or an ongoing process whereby solutions to common problems are conveyed to all translators through rigorous quality control. This study aims to evaluate both methods to ascertain the most efficient, thorough and cost-effective for sponsors. Method: Eight projects were reviewed. Four included a harmonisation meeting via teleconference with translators from each target language and the instrument developer. During the meeting, the developer and project manager discussed each item and ensured that it had been correctly conveyed in all language versions. Four other projects were harmonised through a detailed concept elaboration, created in collaboration with the developer. This document was continually updated; wherever problems arose, the resolution was incorporated. The document was consulted by translators at each step of the process. Each method was evaluated to determine the optimal process. Results: Both methods achieved harmonised translations. The first added at least a week to the timelines, with the cost to the sponsor also significantly higher, though translators felt it useful to speak with the developer. Several translators noted the value of ongoing harmonisation as per the second methodology; with the first method, the meeting occurred after back translation, and therefore changes may occur later in the validation process that are not subject to formal harmonisation. In contrast the second methodology provides support throughout, and includes developer input. Conclusion: The harmonisation procedure is key to the translation process, and both methodologies achieved harmonised translations. However, the less formal approach shortened the timeline and reduced the cost for the sponsor, without sacrificing harmonisation.