Abstract : Objective To analyze and evaluate the comparabilty ，consistency and bias of measurement results for urine K-Ig and λ-_lg from two measurement procedures. Methods The levels of k-Ig in 162 cases and λ-Ig in 132 cases of urine specimens were measured once by BN II ( comparative measurement procedure, X) and BA400 ( candidate measurement procedure, Y) respectively. ESD method was used to eliminate outliers, scatter plots, difference plots. Bland-Altman plots were applied to analyze the general trend of Y value changing with X value, the characteristics of underlying difference between two measurement procedures, and evaluate their consistency. Arithmetic mean or median were applied to estimate bias preliminary according to the distribution states of different values between the two measurement procedures. The comparison between the two groups of paired samples was performed by Wilcoxon signed rank test. Derming and Passing- Bablok regression models were selected to fit scatter plots and calculate the biases and confidence intervals at medical decision levels. The values of less than or equal to +12.5% was considered as the acceptable criteria. Results The measured results of 146 pairs of urine k-Ig and 122 pairs of urine λ-Ig were screened respectively by ESD test, scatter plots and difference plots. An approx imately linear relationship of the measured values between the two procedures was seen in scatter plots, but mixed variability ( standard deviation and cefficient of variation ) appeared in difference plots. The biases with 95%CI of urine K-Ig were estimated as -1.47 (-1.89 to -0.97) mg/L in low concentration and 5.98% (3.20% to 8.76%) in high concentration respectively. The biases with 95% CI of urine λ-g were estimated as 1.70 (1.26 to2.15) mg/L in low concentration and 18.87% ( 14.03% to 23.70%)in high concentration respectively. The measured results of urine K-Ig and λ-Ig showed abnormal distribution. Wilcoxon test suggested that the measured results of urine k-Ig showed no significant difference between the two procedures ( P>0.05) , however the difference of the measured results of urine λ入-Ig was statistically significant ( P>0.05). The consistency analysis showed that differences in the measured results of urine k-Ig and λ-g between the two procedures were statistically significant ( P<0.05). The points within LoA ran-ges were accounted for 94.52% to 96.46%，but LoA with 95%CI exceeded +12.5%，so it could not be considered that the two measurement procedures were in good consisteney. Regression analysis showed that the confidence intervals of biases of urine K-Ig and λ-g at 14.40 mg/L and 7. 80 mg/L of the medical decision level respectively met the acceptable criteria. The intercepts and slopes of regression equation with 95%CI indicated that the measured results of urine K-Ig showed systermatic and proportional differences between the two measurement procedures, while the the measured results of urine λ-Ig showed only proportional difference. Conclusion The results of two measurement procedures were different in detecting urine light chains, so they could not be replaced each other. The margins of LoA from the two procedures were not acceptable in clinical practice. It was not considered that the two measurement procedures were in good consistency.