Objective: This study was designed to investigate the clinical microbiology of fungal ball (FB) rhinosinusitis by culturing fungal clumps collected under endoscopic surgery. Methods: From April to November of 2012, fungal clumps were sampled by endoscopic surgery from patients diagnosed with FB using clinical and histopathological methods. The specimens were subjected to smear microscopy, and cultured for bacteria and fungi analysis. Results: Out of the 81 specimens from 80 patients, 69 (69/81, 85.19%) specimens were detected a mixed infection of bacteria and fungi. However, only 25 (25/81, 30.86%) specimens resulted in fungal growth. There were 12 (12/81, 14.81%) specimens with fungal infections alone. The cultured fungi included 36 strains belonging to five genera, and most of them were Aspergillus spp. (30/36, 83.3%). The cultured bacteria included 94 strains belonging to 16 genera, and the most frequently seen was Staphylococcus spp. (23/94, 35.94%). When it was fungal and Pseudomonas aeruginosa mixed infection, the fungal growth was inhibited (P = 0.002). Conclusion: Patients with fungal ball usually have mixed fungal and bacterial infections. The fungi from these samples are sometimes difficult to culture, which may be the result of the inhibition by bacteria in vitro and in vivo.