Experiments have been conducted to investigate surface roughness effects on the evolutions of loss and deviation downstream of a compressor blade row. Two cases - smooth (k+ = 1.27) and rough (k+ = 38.92) - have been investigated. Roughness has been attached to the blade suction side using a spray type glue gun and emery grain. At x/c = 0.2, 0.3 and 0.5 (downstream of the cascade), a five-hole probe has been used to measure the total pressure, mean velocity, and deviation at the mid-span. Static pressure taps on the blades have been used to measure the blade loading. When roughness is increased, the loss is larger and the loss increases more rapidly in the axial direction, indicating enhanced mixing. The deviation also increases at every measurement plane when roughness is increased. In addition, pitch-wise deviation distribution becomes uniform at x/c = 0.5 due to enhanced mixing.