Heparin derivatives (I) comprising a low molecular weight heparin chain covalently linked to biotin are new. Independent claims are also included for: (1) a process for preparing (I); (2) use of avidin or streptavidin for neutralizing (I). ACTIVITY : Anticoagulant; Cerebroprotective; Neuroprotective. MECHANISM OF ACTION : Factor Xa inhibitor; Factor IIa inhibitor.