Background: Human T-cell Lymphotropic Virus type I (HTLV1) infection has been reported in patients with a variety of skin lesions in some parts of the world, especially in endemic areas. Infective Dermatitis associated with HTLV-1 (IDH) is the prototypic dermatologic manifestation of infection. However, to the best of our knowledge, it has not been reported in Iran as an endemic area yet. It is aimed to investigate the prevalence of HTLV1 infection among patients with common endogenous dermatitis. Methods: During a cross-sectional study, blood samples of 100 patients with both clinical and pathological diagnoses of common endogenous dermatitis including atopic, seborrheic, and nummular dermatitis who were referred to the Dermatology Clinic of Ghaem and Imam Reza Hospitals, Mashhad, Iran were obtained and evaluated for the presence of anti –HTLV-1 antibody using the ELISA method. The Polymerase Chain Reaction (PCR) for HTLV-1 was conducted in cases where the anti-HTLV1 antibody was positive. Statistical analysis was performed using SPSS version 16, Chicago, IL, USA. Results: Among 100 samples, two cases including erythrodermic dermatitis and atopic dermatitis were positive according to the ELISA method (2.0%). The dermatitis in HTLV1-positive patients was erythematous, scaly, with a generalized distribution and a recurrent nature, but did not complete the Infective Dermatitis (ID) criterion. Conclusion: In Iran as an endemic area, HTLV1-associated dermatitis may be present as recurrent generalized erythematous and scaly rash instead of known typical features of infective dermatitis.