Background: The purpose of this study is to evaluate the efficacy of the treatment for the diarrhea due to Cryptosporidium, which is prevalent in lambs, via the concentrations of Serum Amyloid A (SAA) and Haptoglobin (Hp). Although there are experimental studies in this field, there are quite a few studies on the lambs which are infected naturally. Methods: In this study, stool samples were collected from the lambs that were affected with diarrhea and Cryptosporidium was detected via the rapid test kit (Bio-X Diagnostics S.A. Rochefort/Belgium). Following this procedure, 15 lambs were included in the study by examining same stool samples microscopically and 50 mg/kg of paromomycin sulphate (Huvepharma) was administered to the lambs in which Cryptosporidium spp. was detected for five days as a treatment. 10 healthy lambs formed the control group. Blood samples were taken from all lambs to measure SAA and Hp in the pre and post treatment stages. In the serums obtained from blood samples, concentrations of SAA and Hp were measured in ELISA by using commercial kits. Result: In the lambs with Cryptosporidium, concentrations of SAA and HP were as (SAA; 20,62±4,83 ng/mL HP; 2,63±0,77 µg/mL) in pre-treatment and as (SAA;12,93±3,27 ng/mL, Hp; 1,59±0,73 µg/mL) in post-treatment stage while they were as (SAA;10,07±2,49 ng/mL, Hp; 1,03±0,59 µg/mL) in the control group. In the pre and post treatment stage measurements, a statistically significant difference (p less than 0,05) in the values of SAA and Hp was found between the control group and the lambs wit diarrhea due to Cryptosporidium. It was suggested that this might have occurred as a result of inflammatory response against Cryptosporidium. In the light of these findings, it is asserted that routine measurements of SAA and Hp concentrations of the lambs with diarrhea due to cryptosporidiosis could be beneficial in the following up the treatment, determining the severity of the infection, choosing the right method for treatment and monitoring the efficacy of the chosen treatment method and in detecting subclinical diseases in veterinary medicine.