Gerlovo or Gerilovo () is a small geographic and ethnographic region in Northern Bulgaria, a hilly fertile valley in the northeastern Balkan Mountains, south of the Ludogorie region. It lies between the Lisa, Preslav-Dragoevo and Kotel-Varbitsa mountains and covers much of Varbitsa municipality of Shumen Province, with smaller parts in Omurtag municipality (Targovishte Province) and Kotel municipality (Sliven Province).