To compare the accuracy in scoring of vignettes of 2 cognitive screening tests—the Mini Mental State Examination (MMSE) and the Short Orientation Memory Concentration Test (S-OMC). Within group comparison. Academic institution. A total of 74 student nurses. Participants received instruction on the scoring of each test and were then asked to score 6 videotaped clinical vignettes. Scores allocated by participants on the vignettes for the MMSE and S-OMC. The proportion of participants assigning the correct total score to the vignettes was low (MMSE 53.2%, S-OMC 66.7%), and the difference in accuracy between tests was significant (P = .005). The total scores that were assigned resulted in misclassification across all 4 caseness cutoffs within each test (MMSE 0.9%-5.9%; S-OMC 1.4%-2.7%). The differences in correct caseness placement between the 2 tests were significant only for the moderate impairment cutoff, where the S-OMC achieved greater correct caseness placement. The high proportion of scoring mistakes overall has implications for the use of both the tests in routine clinical practice but in particular for the MMSE. An increased awareness is needed in clinical settings and among tests developers, of the likelihood of, and implications arising from, variations in scoring accuracy. In the current study, the S-OMC was scored more accurately than the MMSE.