Failure to follow-up nonurgent, clinically significant test results (CSTRs) is an ambulatory patient safety concern. Tools within electronic health records (EHRs) may facilitate test result acknowledgment, but their utility with regard to nonurgent CSTRs is unclear. We measured use of an acknowledgment tool by 146 primary care physicians (PCPs) at 13 network-affiliated practices that use the same EHR. We then surveyed PCPs to assess use of, satisfaction with, and desired enhancements to the acknowledgment tool. The rate of acknowledgment of non-urgent CSTRs by PCPs was 78%. Of 73 survey respondents, 72 reported taking one or more actions after reviewing a CSTR; fewer (40-75%) reported that using the acknowledgment tool was helpful for a specific purpose. Forty-six (64%) were satisfied with the tool. Both satisfied and nonsatisfied PCPs reported that enhancements linking acknowledgment to routine actions would be useful. EHR vendors should consider enhancements to acknowledgment functionality to ensure follow-up of nonurgent CSTRs.