PURPOSEWe compared the completeness of data collection using paper forms and using electronic forms loaded on handheld computers in an offi ce-based patient interview survey conducted within the American Academy of Family Physicians National Research Network. METHODSWe asked 19 medical assistants and nurses in family practices to administer a survey about pneumococcal immunizations to 60 older adults each, 30 using paper forms and 30 using electronic forms on handheld computers. By random assignment, the interviewers used either the paper or electronic form fi rst. Using multilevel analyses adjusted for patient characteristics and clustering of forms by practice, we analyzed the completeness of the data.RESULTS A total of 1,003 of the expected 1,140 forms were returned to the data center. The overall return rate was better for paper forms (537 of 570, 94%) than for electronic forms (466 of 570, 82%) because of technical diffi culties experienced with electronic data collection and stolen or lost handheld computers. Errors of omission on the returned forms, however, were more common using paper forms. Of the returned forms, only 3% of those gathered electronically had errors of omission, compared with 35% of those gathered on paper. Similarly, only 0.04% of total survey items were missing on the electronic forms, compared with 3.5% of the survey items using paper forms.CONCLUSIONS Although handheld computers produced more complete data than the paper method for the returned forms, they were not superior because of the large amount of missing data due to technical diffi culties with the handheld computers or loss or theft. Other hardware solutions, such as tablet computers or cell phones linked via a wireless network directly to a Web site, may be better electronic solutions for the future.