The purpose of this study was to investigate the impact of using black plum (Prunus salicina) and black cherry (Prunus cerasus) juices in the alleviation of the side effects resulting from multiple sclerosis (MS) in rats. Chemical composition and phytochemical screening of the two fruits were carried out in addition to the estimation of the antioxidant activity of the fruit juices in vitro. In the biological experiment, thirty adult male albino rats (weighing 135 to 145 g) were used, six of them were served as normal control which remained on the basal diet during the period of the experiment. The remaining groups were injured with cuprizone in a dose of a 3 g / kg diet, one of them was left as a positive control (MS control) while the other three groups were treated daily with the juices of black plum, black cherry, and their mixture (1:1 v/v) in a dose of 15 ml/kg b.wt. using a stomach tube. The weight gain of the rats and food efficiency ratio was calculated. At the end of the experiment, the rats were sacrificed, and their blood was drawn for analysis. The results showed that the weight gain and food efficiency ratio of the positive control decreased significantly as compared to the normal control while significant increases in their values were seen in the three treated groups as compared to the positive group. The findings showed that the levels of serum ALT and AST increased while the level of serum albumin decreased significantly in the positive control. The treated groups with the juices revealed significant improvements in these liver parameters where significant decreases in both ALT and AST and a significant increase in serum albumin were observed. As for serum creatinine, which is a kidney function test, the results indicated that the treated groups with the examined juices exhibited a remarkable decrease in their serum creatinine in comparison with positive control at p < 0.05. On the other hand, significant decreases in serum levels of total cholesterol, triglycerides, and LDL-c and a significant increase in HDL-c were noticed in the treated groups. In conclusion, significant improvements in the liver and kidney functions of MS rats have been achieved by using black plum and black cherry juices or their mixture which was probably attributed to their content of phenolics, flavonoids, and anthocyanins. Key words: Black plum – black cherry – DPPH – lipid profile – liver function tests – MS.