Ziziphus spina [christti] is a naturally distributed tree in subtropical, arid and semi-arid parts of Iran. It is ecologically and economically important due to its tolerance to drought and salinity. Most tree seeds are infected with parasitic and saprophytic microorganisms which decrease the seed germination and seedling establishment. The goal of this paper was to evaluate the ability of selected chemical solutions to inhibit the growth of variety of microbial contaminants in Z. spina Contaminants were identified according to their morphological and cultural characteristics. Bacterial contaminants included Xanthomonas sp. While Fungal isolates were Fusarium, Penicillium, Alternaria, Rhizopus, and Aspergillus. Our experiment reveals that 4% NaOCl followed by benomyl is the best sterilization treatment for Z. spina [christti] seeds, since the highest number of germination and highest number of sterilized seeds was observed after this treatment.