Objective: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most frequent genetic enzymatic disorder in humans. G6PD is inherited as an X-linked recessive gene and encodes a vital housekeeping enzyme. The predominant variant of G6PD is named Mediterranean, often associated with Favism. Most G6PD-Mediterranean subjects also have a silent transition (C1311T). Materials and Methods: In the present study 1065 simple randomly selected blood samples of male donors from Ahvaz Blood Bank, using fluorescent spot test to determine G6PD deficiency in Khuzestan province. G6PD deficiency was found in 126 samples, 70 out of 126 samples were G6PD Mediterranean and the rest of them were shown other variants of G6PD deficiency including Chatham (19 samples), Cosenza (5 samples) and undefined G6PD gene mutation (32 samples). The association between C1311T silent polymorphism in all the G6PD deficiency samples and 70 male controls in Khuzestan province in Iran were studied. Screening was carried out by PCR-RFLP method. Results: Prevalence of C1311T polymorphism was 92.8% among 70 Mediterranean samples and 15.7% among control group respectively. No patient was found for C1311T polymorphism in non-Mediterranean(Chatham and Cosenza) G6PD deficiency group. Conclusion: Statistical analysis showed a strong association between C1311T polymorphism and G6PD-Mediterranean (p<0.001). However, association between C1311T polymorphism and non-Mediterranean G6PD deficiency did not confirm.