Effect of chromium content in the range of 0.05-0.91 wt% on the microstructure and mechanical properties of Cr-Ni-Cu low alloy steel weld metal was investigated. All welds were prepared by manual metal arc welding technique in flat position. Microstructure of the welds was examined by optical and scanning electron microscope in both columnar and reheated regions of the weld metal. The results showed increase in acicular ferrite and microphases formed at the expense of primary ferrite and ferrite with second phase with steady refinement of microstructure. According to these microstructural changes, yield and ultimate tensile stresses, Hardness and Charpy V-Notch impact toughness increased, whereas elongation decreased. Increase in Charpy impact value is thought to be due to fine dispersed spheroidized dark microphases at high chromium contents.