The study was conducted on patients infected with Giardia lamblia, who were admitted to Samarra General Hospital and some private laboratories in the city of Samarra / belonging to Salah al-Din Governorate, the age groups ranged from (1-40) years, the work was completed during the period from 10/2/2021 to 2022 /5/1. Cases of parasite infection were diagnosed by examining faeces samples by direct swab method using a light microscope to detect the trophic and cystic phases. The current study examined 585 faecal samples, and 76 were infected. The study includes its effect on some biochemical variables. Three aspects include: the first side is hormones (cholecytokinin and somatostatin hormone), the second side is vitamins (Vitamin B12 and (Vitamin A), and the third side includes elements including sodium and potassium. The results showed that there was a significant increase in the levels of each of Colcytokinin 156.0 ± 15.5 and Somatostatin 122.7 ± 18.1 compared with the control group. The results recorded a significant decrease in the concentration of each of sodium ions 81.8 ± 13.8 Na + and potassium 1.737 ± 0.285 compared to the control group. The results showed that there was a significant decrease in the concentration of vitamin B12 in the group of patients with 5.25 ± 1.79 compared with the control group, while there was no significant difference in the concentration of vitamin A among the patients with 1.149 ± 0.455 compared to the control group.