The present invention relates to a method of producing a hydroxyalkyl starch derivative, said hydroxyalkyl starch having a structure according to formula (I) comprising reacting - hydroxyalkyl starch o formula (I) at its optionally oxidized reducing end or - a hydroxyalkyl starch derivative, obtainable by reacting hydroxyalkyl starch of formula (I) at its optionally oxidized reducing end with a compound (D), said compound (D) comprising - at least one functional group Z1 capable of being reacted with the optionally oxidized reducing end of the hydroxyalkyl starch, and at least one functional group W, with a compound (L) comprising at least one functional group Z1 capable of being reacted with said hydroxyalkyl starch, or at least one functional group Z2 capable of being reacted with functional group W comprised in said hydroxyalkyl starch derivative, and at least one functional group X capable of being reacted with a functional group Y of a further compound (M), wherein said functional group Y is selected from the group consisting of an aldehyd group, a keto group, a hemiacetal group, an acetal group, and a thio group. The present invention further relates to the hydroxyalkyl starch derivatives as such ans a pharmaceutical composition comprising the hydroxyalkyl starch derivatives.
