In one aspect, present invention provides a recombinant mutant human factor VIII having increased expression and/or secretion as compared to wild-type factor VIII. In certain embodiments, the recombinant factor VIII includes one or more amino acid substitution(s) selected from the group consisting of I86, Y105, A108, D115, Q117, F129, G132, H134, M147 and L152. In other aspects, the present invention provides FVIII encoding nucleic acids, FVIII-expression vectors, as well as methods of using the modified FVIII genes in the treatment of FVIII deficiencies, such as hemophilia A.