Hepatitis B surface antigen (HBsAg) testing is the only method currently used in laboratories to diagnose hepatitis B virus (HBV) infection in febrile patients. The South-South area of Nigeria does not currently have data on the prevalence of anti-HBc-IgM. The main goal of this study was to identify the serological evdience of anti-HBc-IgM markers among febrile patients in Port Harcourt, Nigeria. Following the manufacturer's standard operating procedures, 92 febrile patients were tested for HBc IgM antibody during cross-sectional research from November 2020 to October 2021. The prevalence of anti-HBc IgM antibodies (35.9%) and anti-HBc-IgM negatives was 64.1%. The prevalence of anti-HBc- IgM antibody was higher among older age groups (44.7%), females (53.3%), singles (42.9%), tertiary educational level (42.2%) and civil servants (47.4%). None of the variables evaluated was significantly associated with the prevalence of HBc IgM. This study shows that 35.9% febrile patients have anti-HBcIgM as the only serological evidence of HBV infection. This study identifies a possible danger of HBV transmission from febrile individuals who test positive for anti-HBc to the general population. Anti-HBc-IgM antibodies are prevalent in Port Harcourt among feverish patients. In Nigeria, screening patients who are feverish for anti-HBc IgM should be encouraged. This research represents the first evaluation of anti-HBc IgM in the South-South region of the nation.