Haematopoietic stem cell transplant (HSCT) recipients lose immune memory of exposure to infectious agents and vaccines accumulated throughout their lifetime and therefore need to be revaccinated. We aimed to evaluate the influence of different factors on hepatitis A virus (HAV) immunity in both child and adult HSCT recipients living in an intermediate endemic region, Turkey. Eighty patients (age range 2·5-57 years) who had HAV serology prior to HSCT were evaluated. The prevalence of HAV seropositivity was 85% (n=68) before HSCT. There was no history of HAV vaccination before HSCT in children and HAV vaccine was not available in Turkey 10 years ago, so it was assumed that all seropositive patients reflected natural immunity. After the exclusion of six patients with autologous HSCT, the remaining 62 seropositive and allogeneic patients were included in this retrospective study. The duration of HAV seropositivity was estimated using the Kaplan-Meier method, log-rank analysis and Cox regression models. Estimated mean time to loss of HAV seropositivity was 48·6 months after transplantation. Patients who were older (⩾18 years) at transplantation and who had older (⩾18 years) donors became seronegative later (P<0·05). Cox backward-stepwise regression confirmed that older age of recipient at transplantation was the only significant parameter for HAV seropositivity (P<0·05). HAV-inactivated vaccine might be recommended later to older HSCT recipients in intermediate endemic regions.