This study, which was conducted in the city of Mosul, through collected 1200 samples from the stool of patients with diarrhea attending hospitals and private clinics for the period from the beginning of January 2019 to the end of December 2019, those whose ages ranged from less than a year-60 year, and for both sexes and by reality 700 samples stool for males and 500 samples stool for females. Samples were collected in clean, sterile, and sealed 40ml plastic bottles. Patient information is noted, name of the parasite, history, sex, age, address. The result showed that climate and temperature have a significant effect on increase the incidence of intestinal parasites through the direct effect on the increase in infection rate. This effect was the temperatures are suitable for converting the cyst into the trophoizote and fatal phase . The results showed that the infection rate in Mosul governorate with intestinal parasites is 23.83%,which is Entamoeba histolytica & Giardia lamblia, The result showed the number of infected males 193 with an infection rate (27.57%) which is higher than the number of infected females 93 with an infection rate (18.6%) of the total infections and shown the highest percentage infection of intestinal protozoa, parasites occurred in May it has reached (61%) while the lowest percentage of infection was in January (7%). The showed the percentage of intestinal protozoa, parasites infection, according to the age, the highest rate of infection in age group (0-10) (25.09%) while the age group (10-30) recorded the percentage of infection (21.44%), the age group (30-60) percentage of infection is (19.56%) the percentage of intestinal protozoa, parasites infection, according to the age, the highest rate of infection in age group (0-10) (25.09%) while the age group (10-30) recorded the percentage of infection (21.44%), the age group (30-60) percentage of infection is (19.56%), showed the percentage of intestinal protozoa parasite infection, according to the seasons of year the highest rate of infection in spring (32.66%) while the Summer (30%), the autumn recorded the percentage of infection (22%).