Physicians and patients have received inaccurate medical laboratory test results that have put patients at risk. The purpose of this study is to determine the moral reasoning level of medical laboratory professionals. The theoretical framework that guided this study is grounded by the theories of cognitive development. The study used a population survey and Defining Issues Test, version 2 (DIT-2) questionnaires to collect data. Forty-seven participants from a medical laboratory were surveyed, and hypotheses were tested between moral reasoning scores (dependent variable) and age, gender, level of education, years of experience and job type (independent variables). Data were subjected to ANOVA and the results showed that laboratory professionals moral reasoning (N2=26.57, P=30.46) was lower than that of other health care professionals. Training in ethics and moral reasoning are some of the recommendations made. Moral reasoning forms the basis for ethical behavior and good decision making; this is limited in people with poor moral reasoning score, which could result in incorrect laboratory results being reported to patients and physicians. Decisions made by medical laboratory professionals affect patients treatment and care.