A Factor VIII derivative of formula (I): wherein: B represents C2 to C10 alkylene m represents 0 or an integer from 1 to 19, n represents an integer from 1 to 20, and the sum of m and n is from 1 to 20 P represents a mono or polyradical of Factor VIII obtained by removing m+n carbamoyl groups from the side chains of glutamine residues in Factor VIII and M represents a moiety (M1) that increases the plasma half-life of the Factor VIII derivative or a reporter moiety (M2) or a pharmaceutically acceptable salt thereof.
