According to WHO's regional office, 25 cases of Marburg virus disease (MVD; including 1 laboratory-confirmed by WHO reference laboratory and 9 deaths) have been reported since February 7, 2023, in Kié-Ntem Province. The source of acquisition is unknown. Contact tracing is underway. MVD had never been reported in Equatorial Guinea. MVD is a filovirus that is distinct from Ebola. Travelers going to the affected area should avoid contact with bats and direct contact with blood or bodily fluids of acutely ill patients.