Learning Objectives:  To help clarify which ePRO modality (IVR, IWR, Handheld) is appropriate for specific studies through providing three examples of diary requirements and appropriate modalities.  Emphasize making this decision early in the planning process.  Methods:  Examples for three scenarios requiring patients to record their PRO data electronically were drawn up based on experience to illustrate how making appropriate modality choices can minimize patient burden and reduce costs.   Scenario One - 10,000 patient global vaccine study.  Scenario Two – 500 patient global study, daily diary having 40 questions with more than 5 response options.  Scenario Three – 50 GI patients to record their PRO data episodically using a VAS scale daily for over a year.    Results:  Scenario One – Appropriate Choice = IVR: It is expensive and logistically challenging for Sponsors to deploy 10,000 PDAs. Using the IVR global network in place would reduce cost and logistics for the Sponsor and sites.  Scenario Two – Appropriate Choice = IWR: When patients are provided more than 5 response options in a lengthy questionnaire, an IWR would be better since response options are visual. IWR would be better than PDA given the sample size and logistics.  Scenario Three- Appropriate Choice = PDA: A PDA would be most convenient for the patient since they are providing data daily for over a year.  PDA is best for VAS scales since the size of the screen can be controlled.  Conclusions: There is overlap in deciding which ePRO modality to use for a particular clinical study.  It is critical to decide on the modality early when assembling the protocol, so all points can be considered.  Looking at the diary requirements (frequency, length, access) for the study will help the Sponsor to decide which modality is best.  Reducing patient and site burden will allow for greater compliance.