Disclosed are antibodies thereof that bind to coagulation factor XI (FXI) and/or its activated form factor Xla (FXIa), or to a fragment of FXI and/or FXIa, and compositions containing the antibodies. Also disclosed are methods of preparing the antibodies and use of the antibodies for treating and/or preventing coagulation associated conditions such as thrombosis and complications or conditions associated with thrombosis.