Background: Fungal infections of the nose and paranasal sinuses are classified into invasive and non invasive types. Rapid detection and identification of causative fungi is crucial for effective treatment and avoidance of complications. Objectives: To evaluate diagnostic outcome of ELISA detection of galactomannan (GM) in sinus lavage aspirate as a rapid minimally invasive diagnostic test for Aspergillus spp. sinus infection in comparison to fungus DNA detection by nested PCR. Methodology: 95 chronic rhinosinusitis (CRS) patients had manifestations since ≥12 weeks despite of medical therapy were clinically and radiologically evaluated and underwent sinus lavage. Lavage aspirate was used for microbiological examination, PCR testing for Aspergillus DNA and ELISA detection of GM. Results: PCR defined Aspergillus DNA in 56 samples, culture defined 53 positive samples for Aspergillus spp. infection and ELISA detected GM antigen in 49 samples. In comparison to PCR result, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) and accuracy rates of culture were 73.2%, 69.3%, 77.4%, 64.3% and 71.6% while ELISA detected GM antigen were 84.6%, 88.4%, 89.8%, 82.6% and 86.3%, respectively. ELISA results significantly correlated with results of culture and PCR with a positive significant correlation between PCR and culture results. ROC curve analysis defined ELISA detection of GM as more significant predictor for result of culture (AUC =0.792, p<0.001) than PCR test (AUC=0.708, p=0.001). Regression analysis defined PCR testing as the significant predictor for culture results (β=0.529, p<0.001).Conclusion: Fungal CRS causes resistance to conventional treatment and must be investigated before surgical-decision taking. Preoperative ELISA determination of GM antigen could identify patients with aspergillosis sinus infection with high accuracy and specificity. For suspicious cases especially if negative for GM, nested PCR could approach the diagnosis.