Background: Chronic rhinosinusitis is a major cause of morbidity today. Aim: The aim of this study is to find out the prevalence of fungal infection in patients with chronic rhinosinusitis, the clinical presentation of fungal infection and the common fungal organisms. Patients and Methods: This cross-sectional hospital based study was conducted during the period from March 2002 to March 2013 Al-Mukalla city. Three hundred and twenty patients with chronic rhino sinusitis included in this study. All patients underwent nasal endoscopic examination, maxillary sinus surgery, biopsy, fungal culture and CT scan. Results: Thirty two 32 (10%) patients had a fungal infection out of 320 patients with chronic rhinosinusitis. The majority of fungal organisms were Aspergillus fumigates 22 (68.75%), followed by Aspergillus Niger 4(12.50%), Aspergillus Flavus 2 (6.25%), mucormycosis 2 (6.25%) and candidiasis 2(6.25%). CT scan homogenous opacities were noted in 60%. The endoscopic findings showed 10 (31.25%) of patients with chronicrhinosinusitis and 14(43.75%) had chronic rhinosinusitis with bilateral nasal polyposis and 8 (25%) with unilateral polyposis. Regarding correlation between fungal infection and socioeconomic status; the low socioeconomic status noted in 18 (56.25%), followed by middle status in 8 (25%) and high status in 6 (18.75%). Conclusion: CT scan , nasal endoscopy, histopathological examination and fungal culture have made the diagnosis easier. Otorhinolaryngologists must keep in mind fungal infections in their daily practice due to the increasing fungal infections in the recent time.