Abstract: Total attenuation coefficients of normal and cancerous human bladder tissue at 476.5nm,488nm,496.5nm,514.5nm,532nm and 808nm lasers and their linearly polarized laser were determined using the direct and indirect methods,and an integrating-sphere system.The results show that there are significant differences in these total attenuation coefficients of normal or cancerous human bladder tissue at six different wavelengths of laser between the direct and indirect methods(P< 0.05),the differences in the total attenuation coefficients of normal or cancerous human bladder tissue at six different wavelengths between the direct and indirect methods are all obviously bigger than the differences in the total attenuation coefficients of normal or cancerous human bladder tissue at their linearly polarized laser wavelengths between the direct and indirect methods (P< 0.05).