Iron deficiency anaemia has become a major public health issue, especially in women of reproductive age. About 50% of anaemia is caused by iron deficiency anaemia. Numerous statistical procedures based on red blood cell parameters have been developed to easily, quickly, and inexpensively provide a differential diagnosis for the microcytic anaemia. The study aims to evaluate the reliability of the haematological discrimination indices (RBC count, Mentzer index, Red blood cell distribution width index (RDWI), Srivastava index, Green and King index, and Ehsani index) to distinguish iron deficiency anaemia from other causes of the microcytic anaemia. The blood samples were collected from non-pregnant women, and they had the microcytic anaemia. During the study, 101 blood samples were taken. A Complete blood count test and serum ferritin test were performed to calculation of the sensitivity, specificity, positive, and negative predictive value for each discrimination indices. The validity of discrimination indices was evaluated by using Youden's index. In correctly distinguishing iron deficiency anaemia from other causes of the microcytic anaemia, the Green and King index and RBC count showed the highest ability (77%) and (76%), respectively. None of the discrimination indices had 100% sensitivity or specificity. The highest and lowest sensitivity was found for the RBC count and RDWI, at 92% and 70%, respectively. The RDWI had the highest level of specificity (65%), and the Srivastava index had the lowest level of specificity (30%). The highest positive predictive value found for both Green and King, and RDWI was 78%, and the RBC count had the highest negative predictive value (78%). The Srivastava index had the lowest levels of positive and negative predictive values, 67% and 50%, respectively. According to the findings of this study, the most reliable index in the calculation of Youden's index is the Green and King index. It can be used as a pre-diagnostic tool for IDA and other causes of the microcytic anaemia.