Spatially resolved reflectance close to source has received a great deal of attention recently. This research is considered to develop a new noninvasive technique for measuring the optical properties of biological media. Using Monte Carlo simulations, we investigated the influence of third-order parameter on diffuse reflectance and found that the reflectance decreased with an increase of at a short source-detector separation of approximately 0.7-2 transport mean free paths. We show that the effects of two parameters, and secondorder parameter, on the reflectance are contrary. As a result the influence of the second-order parameter on the reflectance is irregular when the condition is not satisfied.