This study aimed to investigate the phytochemicals and cytotoxic properties of aqueous extracts of desert truffle, Terfezia boudieriChatin and its host plant Helianthemum aegyptiacum (L.) Mill. The chemical composition of truffle is relatively higher than its host plants. Carbohydrate content showed the highest rate, but crude lipid showed the lowest rate in truffle and the host plant. Potassium is the highest concentration macro-element, and iron is the highest concentration of micro-element in the truffle and host plant. Compared to the several extracts tested, ethyl acetate extracts of the desert truffle, T. boudieriand host plant H. aegyptiacum (L.) Mill. gave the highest cytotoxic activity against five tested cancer cell lines (the human eye carcinoma cell line MP38, the human central nervous system cell line SF-268, the colorectal carcinoma cell line HCT116, the prostate cancer cell line DU-145 and the breast cancer cell line MDA). The active substances of truffles are more effective than the active substances of host plants in terms of cell mortality rate and nuclear condensation of cancer cells. Human eye cancer cells MP38 treated with truffle ethyl acetate extract showed a greater cell mortality rate than those treated with host plant ethyl acetate extract. Thus, it could be concluded that desert truffles have distinctive metabolites with powerful biological activities, such as antiproliferative activities, compared to the host plant's corresponding metabolites.