OBJECTIVES: To pilot test daily electronic symptom diaries in pediatric chronic constipation (CC) and irritable bowel syndrome with constipation (IBS-C) for approximately one week prior to cognitive debriefing interviews.  METHODS: Separate child and parent eDiary measures of CC/IBS-C symptoms were developed based on concept elicitation interviews with children with CC/IBS-C and their parents.  The eDiaries were completed by 36 children/adolescents (aged 6-17 years) with CC/IBS-C and 30 parents (of 6 month-11 year old children with CC/IBS-C) for 5-9 days prior to cognitive debriefing.  Children and parents were trained to use the eDiary and following the pilot test, children and parents were interviewed separately about their experiences completing the eDiaries and the symptom items.  Item descriptive statistics were calculated using the eDiary data collected during the pilot test. RESULTS: Both eDiaries were well understood, all items were considered relevant, and no symptoms were identified as missing from the eDiaries.  During cognitive debriefing, the children were able to reflect on their experiences of completing the eDiary as opposed to considering hypothetical scenarios to debrief the items.  Although 9 children and 15 parents reported challenges with transmitting data, mean compliance rates were high (94% and 92%, respectively), indicating low levels of missing data and that the eDiaries were easy to use overall.  Mean completion times were 3.72 minutes for children and 3.96 minutes for parents, providing further evidence of low burden.  All item responses were normally distributed and demonstrated expected patterns of response (e.g., most reported 0 or 1 bowel movement daily). CONCLUSIONS: Pilot testing eDiaries prior to cognitive debriefing interviews, especially with children, provides respondents with the experience of completing the eDiary, facilitating a more informed qualitative interview.  Pilot testing also provides preliminary quantitative item performance data and important insights about the usability of eDiaries.