Single crystal EPR studies of Mn(II)-doped zinc ammonium phosphate hexahydrate (ZnNH₄PC₄·6H₂O) have been reinvestigated at room temperature. Single crystal rotations along the three orthogonal axes indicate that the spin Hamiltonian parameters for the interstitial site are:g_xx = 1.966,g_yy = 1.972,g_zz = 1.976;D_xx = -12.28 mT,D_yy = -2.09 mT andD_zz = 14.37 mT;A_xx = 9.06 mT,A_yy = 9.06 mT andA_zz = 11.09 mT;a = -0.11 mT. These parameters differ considerably from the previous report of Chand and Agarwal and indicate the orthorhombic nature of the paramagnetic impurity. The impurity is found to enter the lattice interstitially, in contrast to earlier prediction of substitutional position. The percentage covalency of the Mn-0 bond has been estimated.