The influence of crystal orientation on the magnetic properties of 3% Si-Fe single crystals was investigated by measuring iron losses and observing magnetic domain patterns in TiN-coated and chemically polished specimens. The iron loss was reduced in a TiN-coated sample whose β angle was less than 4 degrees and increased in a sample whose β angle was larger than 4 degrees. The improvement in the iron loss was due to a decrease in eddy current loss that corresponded to a decrease in the magnetic domain width caused by the tensile stress effect of the TiN coating. In the sample whose β angle was larger than 4 degrees, the eddy current loss did not change due to the TiN coating because the magnetic domain width was almost the same under alternate magnetization. Additionally, hysteresis loss increased because of increase magnetic coercive force.