Sir,

I read with interest the published article by Kalantari *et al*.\[[@ref1]\] in your journal recently. The authors presented the zero prevalence for occult hepatitis B virus (HBV) in patients on hemodialysis in Isfahan. However, I would like to highlight some points about occult HBV among them. Occult HBV patients may be seronegative (both hepatitis B core antibody \[anti-HBcAb\] and hepatitis B surface \[anti-HBs\] antibody are negative) or seropositive (anti-HBc is positive with or without anti-HBs positivity).\[[@ref2]\] Occult HBV is predominantly detected in patients with isolated anti-HBc (hepatitis B surface antigen \[HBsAg\] negative, anti-HBs negative and anti-HBc positive). Ramezani *et al*. showed that 1% of patients on hemodialysis with HBsAg-negative had occult HBV with positive HBV DNA in their serum without considering their HBcAb status.\[[@ref3]\] It seems that if the authors would done in all hemodialysis HBsAg-negative group, the result would be clearer and it seems that the occult HBV had underestimated in their study group. However, currently available evidence suggests a relatively high prevalence of occult hepatitis B in hemodialysis patients. Conventional serologic testing used in most hemodialysis centers is not able to identify the occult infection.\[[@ref4]\]

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