Thymoquinone (TQ) has been widely used in traditional medicine for the treatment of many diseases, to support the circulatory and immune system and to protect general health. Moreover, it is used as a nutritional supplement for preventive and therapeutic purposes in the respiratory, digestive and urinary systems. Secretion granules in the cytoplasm of mast cells contain primary mediators such as histamine, neutral proteases such as tryptase and chymase, and cytokines such as interleukin-4 (IL-4) and interferon-gamma (IFN-γ). 35 Sprague Dawley adult female rats were used as the study material. The rats were randomly assigned to five groups. First group: 1 ml/kg dose and second group: 2 ml/kg dose of TQ prepared at 1/1 (v/v) of ethanol and saline was intraperitoneally injected regularly in the rats daily for 42 days. Third group: 10 mg/kg dose and fourth group: 20 mg/kg dose of TQ was administered orally with the aid of a gavage probe. Fifth group was the control group in which no intervention was made. The lowest number of mast cells was detected in the group administered TQ at a dose of 20 mg/kg by oral gavage. It was determined that the numbers of mast cells in the control group and the group treated with TQ at a dose of 1 ml/kg intraperitoneally were close to each other. It was concluded that the increase or decrease between groups in the distribution of mast cells, chymase, IL-4, and IFN-γ cytokine expression may be partially effected in the spleen tissue by substances such as TQ.