Biotinylated heparins (Ia) are new. Biotinylated heparins of formula (Ia) are new. n : 25; X : H or SO 3Na; Y : COCH 3 or SO 3Na; R 1a bond, CO(CH 2) jNH or CO(CH 2) jNHCO(CH 2) kNH; j, k : 1-10; Biot : biotinyl. Independent claims are also included for: (1) a process for preparing (Ia); (2) use of avidin or streptavidin for neutralizing (Ia). [Image] ACTIVITY : Anticoagulant; Cerebroprotective; Neuroprotective. MECHANISM OF ACTION : Factor Xa inhibitor.