Recently, a novel virus, designated as SEN virus (SENV) wasdiscovered, SENV belongs to the family of TT viruses. The aim of this studywas to investigate the prevalence of SENV in blood donors and in patientswith liver diseases in Egypt. This study was conducted on 100 blood donorsand 50 patients with different forms of liver diseases. Cases under study weresubjected to determination of liver enzyme (ALT & AST) , detection ofHBsAg, detection of serum antibodies against HCV, detection of serumantibodies against HIV and detection of SENV DNA (SENV-D and SENV-H)by PCR. SENV DNA was not detected in any of the blood donors while it wasdetected in 3 out of 50 patients with liver diseases.