OBJECTIVE: To determine the relations of parameters of nerve conduction study (NCS) and total symptom score (TSS), neuropathy impairment score (NIS) in diabetic polyneuropathy patients. METHOD: Seventy three patients with diabetes mellitus were included in the study. The NIS, TSS was scored in each patient by a single examiner. NCS was performed on median, ulnar, tibial, peroneal and sural nerves. Distal latencies, amplitudes and conduction velocities of compound muscles and nerves were used as parameters of NCS. The transformed individual amplitudes and nerve conduction velocities were graded in relation to the mean values and standard deviations of our control group study. Then, composite score (CS) was calculated in each individual and was correlated to the NIS, TSS using correlation analysis. RESULTS: There was a significant linear relationship between CS and NIS-LL (neuropathy impairment score-lower limb) (r=0.718, p<0.01) CONCLUSION: This study showed significant correlations between composite score and NIS-LL. Thus, composite score appears to reliably represent the objective neurologic findings. In addition, NIS-LL would be useful in determining the progression of peripheral polyneuropathy in diabetic patients.