As the use of electronic health records increases, it becomes necessary to address their global impact on nurses’ productivity in hospitals. A retrospective cross-sectional study was conducted to explore the impact of electronic health records on nurses’ productivity and to examine whether the impacts are moderated through case-mix index or adjusted patient-days. Two sources of data were linked and analyzed for years 2007 and 2008: the American Hospital Association survey and the Centers for Medicare & Medicaid Services data. Almost two-thirds of the respondent hospitals in both years (63.9% in 2007 and 68.4% in 2008) had a high electronic health record index (≥5). Hospitals with higher penetration of electronic health records had more RNs employed (coefficient = 0.234, P = .002) compared with hospitals with low penetration of electronic health records, even when controlling for adjusted patient-day volumes. This difference decreased for hospitals with higher case-mix index values. The study findings fail to suggest any financial savings or superior productivity in nurses due to usage of electronic health records.