Electromagnetic scattering by a circular cylinder, characterized by D B, DB and D B boundary conditions, is studied. These boundary conditions deal with the normal components of electromagnetic flux densities and their normal derivatives. Electromagnetic behavior of a circular cylinder satisfying a pair of conditions among these different sets of boundary conditions is first investigated in free space. The response of cylinder placed in free space is discussed for both T Mand T E-polarized incident fields, with respect to axis of the cylinder. The results are then extended by placing these boundaries in chiral and chiral nihility mediums. Numerical results for these boundaries placed in free space, chiral and chiral nihility mediums are given and compared with those of DB cylinder placed in similar media.