OBJECTIVES: The patient burden of completing large numbers of patient-reported outcome (PRO) items is often a concern; particularly when PROs must be completed daily, or at multiple timepoints over long studies.  However, as ePRO and mPRO (technology that utilizes patients’ personal tablets and smartphones) methods advance, PRO completion becomes quicker and easier.  How long does it actually take patients to complete ePROs?  How burdensome do patients find ePRO completion? METHODS: ePRO allows collection of the time taken to complete a set of PRO items.  We summarise data from four qualitative studies across a range of health conditions (fibromyalgia, a women’s health condition, pediatric constipation and pediatric irritable bowel syndrome).  In all four studies, small samples of patients (n=20-65) completed an ePRO diary daily for 5-9 days during pilot testing prior to cognitive debriefing.  Completion times and missed days were collected.  During the cognitive debriefing interviews patients were asked how burdensome the PRO completion was and if they had difficulty fitting it into their daily routine. RESULTS: The PROs being developed had 15-35 items, but two included skip patterns, reducing the item burden. Average completion times ranged from 2.5-5.5 minutes per diary.  For diaries without skip patterns, mean ‘per item’ completion times were calculated to range from 9.4-15.7 seconds.  The majority of patients (93-100%) reported that the PRO was quick and easy to complete and not burdensome. Missed diary rates were consistently low with only 0-12% of patients missing more than one diary completion in the two studies where this information was collected. CONCLUSIONS: These data provide evidence that patients (including children) can complete ePRO diaries very quickly, don’t find this burdensome, and are happy to complete relatively large numbers of items daily.  If ePROs are carefully designed, using skip-patterns and event driven items, completion burden can be reduced even further.