Freezing and thawing is a prevalent process in mountainous areas as well as in the plains of cold regions. During this phenomenon, soil water freezes as the temperature falls down below zero and then transforms again to liquid when the temperature rises and takes a positive value. In this study, an effort was made to quantify the impact of this phenomenon on variation of the sediment concentration as well as the runoff volume. For this purpose, two series of experiments were conducted in order to evaluate the effect of precipitation and also the injected runoff from upstream on these changes. For the first series of the experiments, a small flume (0.5 m×1m×0.1m), filled with a clay loam soil, was placed under an equipped rainfall simulator which was capable of simulating different rainfall intensities. Being repeated for both control and freeze-thaw samples, all of these experiments were conducted for three rainfall intensities (25, 40 and 60 mm/hr), two slopes (8% and 15%) and three values of initial volumetric soil moisture content (18-20%, 25-27% and 38-40%). Concerning the second series which were performed without any rainfall injection, the previous treatments for slopes and soil moisture contents were considered, while a constant runoff rate (2.5 L/min) was infused to the soil from 2 cm above the upstream flume. Furthermore, in order to study the probable effect of runoff turbidity, one treatment of clear water and two treatments of runoff containing sediment concentrations of 5 and 10 gr/L were also taken into account. The results showed that a freeze and thaw cycle followed by a rainfall event increases the average sediment concentration such that the range of this increase is 3.5-13%, 7.5-21% and 10.5-33% for rainfall intensities of 25, 40 and 60 mm/hr, respectively. However, it was observed that for most cases, this increase in sediment concentration is not followed by a runoff increase because the runoff volume showed only a little increase for experiments performed at high rainfall intensities and high slopes. The accuracy of these results was verified by measuring the soil shear resistance when it was found that freeze and thaw cycle decreased this factor 4-70%. The results of the second set of the experiments, which was performed with runoff injection from the upstream, showed that based on flume slope and initial volumetric soil moisture content, a freeze and thaw cycle can increase the sediment concentration from 11% to 36%.