Overestimation of patients’ health literacy skills is common among nurses and physicians. At Vanderbilt University Hospital (VUH), nurses routinely ask patients the three Brief Health Literacy Screening (BHLS) questions. Data from two studies that recruited patients at VUH, the Health Literacy Screening (HEALS) study and the Vanderbilt Inpatient Cohort Study (VICS), were analyzed to compare the BHLS score recorded by nurses during clinical care with the score recorded by trained research assistants (RAs) during the same hospitalization. Logistic regression models determined which patient characteristics were associated with nurses documenting higher health literacy scores than RAs. Overall, the majority (60%) of health literacy scores were accurate, though nurses recorded meaningfully higher health literacy scores in 28.4% of HEALS patients and 35.6% of VICS patients. In the HEALS cohort, patients who were male and had less education were more likely to have higher health literacy scores recorded by nurses (OR=1.93, 95% CI=1.24-3.00 and OR=0.80, 95% CI=0.74-0.88, respectively). In the VICS cohort, patients who were older, male, and had less education were more likely to have higher health literacy scores recorded by nurses (OR=1.01, 95% CI=1.003-1.02; OR=1.49, 95% CI=1.20-1.84; and OR=0.87, 95% CI=0.83-0.90, respectively). These findings suggest that health literacy scores recorded by nurses for male patients and patients with less education could be overestimated. Thus, healthcare professionals should be aware of this tendency and should verify the results of routine health literacy screening tests, especially in certain patient groups.