Various criticisms have been leveled against psychological testing. A large proportion of the criticism pivots on fairness of test to the various identifiable groups taking the same test. This article discusses the meaning, types and sources of test item bias as well as different methods of detecting it in a testing situation. One of the implications of test item bias in Nigerian educational system is that it blurs the essence of testing which is to reveal the latent ability of examinees. Test item bias also affects the vital psychometric properties of measurement results in terms of validity and reliability. It is recommended that examination bodies should construct test items in such a manner that items are free from writing errors such as wordiness, irrelevancy, offensiveness, and excessive stimulations, so that when an inadequacy exists between groups’ examination scores, the disparity will be attributed to true differences in whatever the test purports to measure in the examinees. The paper emphasizes that educators should take more cognizance of the possibility of test item bias in a testing situation and with this kind of effort, candidates from educationally disadvantaged areas and low socio-economic status would be certain to be fairly treated.