Paper diaries are commonly used in health care and clinical research to assess patient experiences. There is concern that patients do not comply with diary protocols, possibly invalidating the benefit of diary data. Compliance with paper diaries was examined with a paper diary and with an electronic diary that incorporated compliance-enhancing features. Participants were chronic pain patients and they were assigned to use either a paper diary instrumented to track diary use or an electronic diary that time-stamped entries. Participants were instructed to make three pain entries per day at predetermined times for 21 consecutive days. Primary outcome measures were reported vs actual compliance with paper diaries and actual compliance with paper diaries (defined by comparing the written times and the electronically-recorded times of diary use). Actual compliance was recorded by the electronic diary. Participants submitted diary cards corresponding to 90% of assigned times (+/-15 min). However, electronic records indicated that actual compliance was only 11%, indicating a high level of faked compliance. On 32% of all study days the paper diary binder was not opened, yet reported compliance for these days exceeded 90%. For the electronic diary, the actual compliance rate was 94%. In summary, participants with chronic pain enrolled in a study for research were not compliant with paper diaries but were compliant with an electronic diary with enhanced compliance features. The findings call into question the use of paper diaries and suggest that electronic diaries with compliance-enhancing features are a more effective way of collecting diary information.