The College of Science in the Department of Mathematics discussed a seminar entitled (NUMERICAL STUDY AND STABILITY OF DELAY DIFFERENTIAL EQUATIONS OF TUMOR GROWTH AND ITS PARAMETER ESTIMATION PROBLEM) for postgraduate student Ibrahim Makki Khalil. The seminar aims to consider a class of cancerous tumor cells differential equations with time delay that illustrates and represents the interactions of the tumor cells with effector cells include immune response of natural, dendritic and cytotoxic cells.