This study aimed to find the Classical Test Theory (CTT) and Modern Test Theory (MTT) item parameters of the Differential Aptitude Test (DAT) and examined their comparability of them. The item parameters being studied are difficulty level and discrimination index. 5.024 data of the result sub-test DAT were documented by the Department of Psychology and Guidance and Counselling bureau. The parameter of classical and modern test items was estimated and correlated by examining the comparability between parameters. The results show that there is a significant correlation between item parameter estimates. The Rasch and IRT 1-PL models have the highest correlation toward CTT regarding the item difficulty level. In contrast, model 2-PL has the highest correlation toward CTT in the item discrimination index. Overall, the study concluded that CTT and MTT were comparable in estimating item parameters of DAT and thus could be used independently or complementary in developing DAT.