 As of 2006 its total population is 75,073, out of which the population of Ostrów Mazowiecka is 22,560, that of Brok is 1,859, and the rural population is 50,654.Ostrów Mazowiecka County is bordered by Łomża County to the north, Zambrów County to the north-east, Wysokie Mazowieckie County to the east, Sokołów County and Węgrów County to the south, Wyszków County to the south-west, and Ostrołęka County to the north-west.The county is subdivided into 11 gminas (one urban, one urban-rural and nine rural).