This final work describes the way in which the daily diet and physical activity with different intensity, duration and frequency affect the basic functions of the immune system. Excessive physical activity in combination with malnutrition causes a negative energy balance and affects the immune system. Also, excessive daily energy intake has a negative impact threatens the immune system. Consequent, restrictive and over-nutrition can impair the body's ability to fight against pathological microorganisms that can reduce and slow down the basic function of the immune system. Physical activity changes and affects the immune system, depending on the intensity, duration, frequency and duration of physical activity, rest between physical activity phases. Intensive and time-consuming physical activity, which is very common in professional athletes, can adversely affect the immune system. Reduces neutrophil function, phagocytosis activity, increases the concentration of leukocytes and the production of inflammatory and proinflammatory cytokines, increase of the frequency of respiratory infections and general infections and inflammatory conditions. Moderate and regular physical activity has different results. Resulting in increased neutrophil function, adherence, chemotaxis, better proliferation of CD4+ T cells, induction of TNF-α, IL-6 suppression and protection from cancer and various diseases. In general, moderate and regular physical activity results in a positive effect on immune function.