The present invention provides methods of increasing the half-life factor VIII. More specifically, the invention methods of increasing the half-life of factor VIII by substituting amino acids in the A2 domain or in the C2 domain of factor VIII or in both domains. It further provides factor VIII mutants produced by these methods. The invention also provides a method of using receptor-associated protein (RAP) to increase the half-life of factor VIII. The invention also provides polynucleotides encoding the mutant factor VIII, polynucleotides encoding RAP, and methods of treating hemophilia using the polypeptides and polynucleotides of the invention.