Myeloid leukaemia (ML) is a cancer that occurs by the accumulation of abnormally multiplied myeloid cells in bone marrow, peripheral blood, and other related tissue. MST3 is a gene of the GCK family that has a role in apoptosis, along with other cellular functions like cellular differentiation, cell cycle, metabolism, and others. Objectives: The objectives of this study were to count RBCs and WBCs, study MST3 expression in ML and control samples, and perform an in silico correlation study on the KRAS and NRAS genes. Methods: The counting of RBCs and WBCs was carried out using a hemacytometer, the expression of MST3 was studied using RT-PCR, and a correlation study was carried out using GEPIA. Results: RBC and WBC levels in ML differed from the control levels, and the expression of MST3 was found to be upregulated in ML in comparison to controls, with a 2.90–8.65-fold change, with a significant p-value > 0.05. A positive correlation in expression was also found between MST3 and KRAS and NRAS genes, with a significant r value correlation. Conclusions: From this study, it could be deduced that MST3 might have a role in ML pathogenesis, but further research is needed to study its role in the progression of the disease.