Objective To investigate allergen variety of Alternaria alternata in four different culture mediums. Methods Alternaria alternata was grown in four different culture mediums (nutrient broth medium,Czapek-Dox broth medium,Czapek yeast extract medium,and bacteria synthetic medium) for 14 days,and photographed by digital camera. The mycelia extracts of Alternaria alternata were analyzed by SDS-PAGE and Western blotting. Molecular weights of major protein bands and allergens were calculated by Bio1D software. Results Morphological characteristics of Alternaria alternata grown in different culture mediums were distinct. Total of 4,10,11,and 13 protein bands were detected in the extracts of Alternaria alternata mycelia cultured in four culture mediums,respectively. But the most bands of allergens were found in extracts prepared from Alternaria alternata mycelia grown in Czapek-Dox broth medium with Mr of 83 000,27 000,26 000,20 000,12 000,and 10 000,respectively. Total of 1,6,2 and 1 positive reaction bands were found in extracts prepared from Alternaria alternata mycelia collected from four different mediums respectively. One common allergen with Mr of 12 000 was existed in Alternaria alternata mycelia grown in Czapek-Dox broth medium,Czapek yeast extract medium,and bacteria synthetic medium. Some different allergens could be detected in Alternaria alternata mycelia planted in different culture mediums. Conclusion Morphological characteristics,variety,protein quantity,and allergens of Alternaria alternata grown in different culture mediums were different.