摘要:Background Human T cell lymphotropic virus type I (HTLV-1) infection is endemic in specific regions of the world, including northeastern Iran. Besides mother to fetus transmission, it can be transmitted through breast feeding, sexual contact, and blood transfusion. The aim of this study was to determine the frequency of HTLV-1 in children. Materials and Methods This cross-sectional study was conducted on children from 6 months to 14 years of age hospitalized in Imam Reza Hospital between January 2016 and January 2017. HTLV-1 antibody testing was done on all patients admitted within one year, and the positive results were further confirmed by Polymerase chain reaction (PCR). After determining the frequency, the types of feeding and possible transmission ways of the virus were investigated. Results Out of the 1358 children admitted, 758 entered the study and were tested for HTLV-1 antibody. The result was positive in 58 patients (7.65%) who were further tested by PCR and 11 (1.45%) had positive antibody result. Out of the 58 positive children, 28 (48.3%) were male and 30 (51.7%) female. Most of the children were in the age range of 6 to 30 months and breastfed. In terms of location, most of them lived in Mashhad (58.62%). Conclusion Our results demonstrated that the frequency of HTLV-1 antibody among children of 6 months to 14 years was 7.65%. They were tested by PCR and 1.45% were positive. This region therefore still remains an endemic area for HTLV-1 infection.