Immunomodulators from natural products are widely used for the treatment of infectious diseases, allergies, and cancer in traditional Moroccan medicine. The purpose of this study was the study of two plant seeds of Brassica rapa (Turnip) and Raphanus sativus (Radish) used by Moroccans in traditional medicine to enhance immunity. We have prepared three different extracts from seeds using ethanol, Ethyl Acetate, or water. Immunomodulatory effects of these two plant seeds were tested on rabbit immunity cell proliferation (splenocytes, thymocytes, and macrophages) and their functions (IgG production, cytotoxicity, and phagocytosis). The results obtained indicated that only aqueous extract of B. rapa seeds revealed an immunostimulant effect on both splenocyte and thymocyte proliferation with an increase in cytotoxicity of thymocytes (MLR assay). With R. sativus seeds, we observed an important stimulation of thymocyte proliferation and their cytotoxicity under aqueous extract without effect on splenocyte or macrophages. We concluded that aqueous extract of both seeds (B. rapa and R. sativus) possessed immunostimulant properties leading to stimulation of cellular immunity responsible for defense against viruses.