The study was carried out to determine the clinical course and epidemiological pattern of intestinal nematodes in dogs in Upper Egypt, and their impact on various hematological and biochemical parameters. A total number of 120 dogs (Age =1 month to 3 year), both sex and of different breed's size (small and large) were included in the present study. Parasitological, clinical, hemato-biochemical and epidemiological examinations were conducted. Microscopic analysis of fecal samples (n=120) revealed three types of intestinal nematodes: Toxocara canis (n= 28), Toxascaris leonina (n =5), Ancylostoma caninum (n = 4) and mixed infection of Toxocara canis and Dipylidium caninum (n =2) with an overall infection rate 32.5% (39/120). Toxocara canis was predominate type of nematodal parasite infection in the studied population (23.3%). Puppies (0-<3 months) were greatly affected with intestinal nematodes (54.8%), in particularly Toxocara canis (45.2%). Infected puppies showed off food, pale mucous membrane diarrhea abdominal bloating with potbellied appearance and vomiting. Other group of examined animals (n= 54) showed no clinical signs (asymptomatic) however a portion of this group (25.9%) was infected suggesting that absence of clinical symptoms was not an evidence of the absence of infection. Sex and breed showed non-significant differences (P>0.05) on infection rate of intestinal nematodes but season had high impact on nematodal infection The infection rate showed significant (P<0.05) increasing in winter (42.3%) and autumn (43.8%) with a maximum infection rate reported in December (60%) and January (56.5%). Hematological data generated from 35 blood samples of infected and 40 samples of healthy dog populations showed significant decrease (P>0.05) in erythrocytic parameters (RBCs, Hb, PCV) and platelets count in infected group, whereas group differences for TWBCs, neutrophils, monocytes, lymphocytes, eosinophils and basophils were non-significant high. Biochemical data generated revealed significant decrease (P>0.01) in the value of serum total protein in infected group. Liver enzymes showed significant increase (P>0.01) in serum AST, ALT and ALP in infected group compared with healthy one. In conclusion, intestinal nematode in dogs was common in Upper Egypt with infection rate of 32.5% and Toxocara canis was the most common nematode infection (23.3%). They have significant effects on hematological and biochemical parameters suggesting their importance as a health problem in dogs.