BACKGROUND: Many drugs such as atorvastatin are known effective in reduction of serum lipids in dogs, but with a literature review, we did not find report on the field of the effect of chitosan on serum lipid in dogs. OBJECTIVES: The purpose of the present survey was comparative evaluation of the effects of chitosan and atorvastatin on serum lipid profile changes and the influence of time on treatment process in dogs. METHODS: For the management of cholesterol powder induced hyperlipidemia, twenty healthy dogs were randomly divided into four equal groups. Group A (control) included of five dogs that were fed with cholesterol powder (4 gr/kg for 10 days). Group B was similar to group A, but in addition, atorvastatin (5 mg/kg) was administered for 45 days after induced hyperlipidemia. Group C was similar to group B, but chitosan (3 gr/dog) was administered instead of atorvastatin. Group D was a combination of groups B and C, which the combination of atorvastatin and chitosan were fed to dogs with the same dose of previous groups. Blood samples were collected four times on days 0, 10, 40 and 55 after challenge, then serum triglycerides, total cholesterol, HDL-C and LDL-C levels were measured using standard commercial kits. RESULTS: Groups of atorvastatin and chitosan (B and C) and group D were more effective in lowering serum triglyceride, total cholesterol and LDL-C and increase of HDL-C, compared with group A (p<0.05). The greatest decrease was related to group D for triglyceride (105.60±17.49), total cholesterol (119.80±11.39) and LDL-C (36.40±7.57). The greatest increase was seen in group D for HDL-C (36.40±7.57) also. In comparison between two drugs and their effects on lipid profiles, atorvastatin showed a significant difference than chitosan (p<0.05). A combination of two drugs, was more effective compared with single administration of the drugs (p<0.05). CONCLUSIONS: The present survey showed that although both drugs have hypolipidemic activity in dogs, but the effect of chitosan was lower than atorvastatin, so it is not recommended to use chitosan only. Further experimentation needs to elucidate the possible mechanism of the drugs.