Regarding the epidemiology of filariasis in some farm animals 1410 different domesticated animals (308 camels, 297 buffaloes, 157 cattle, 182 horses 175 mules and 291 donkeys) were examined during 2002-2004 at different localities in Sharkia Province, National Cairo Circus and Zoo animals in Giza Governorate. It was found that 159 animals (27 camels, 35 buffaloes and 97 donkeys) showed the clinical picture of filariasis and were infested with microfilariae. Out of 1251 examined apparently normal animals 391 animals (45 cattle, 30 buffaloes, 69 horses, 98 mules and 149 donkeys were found to be infested with microfilariae without any apparently clinical finding. The total incidence of filariasis in some farm animals was 39%. The highest incidence was recorded in donkeys (84.5%) then mules (56%) then horses (37.9%) then cattle (28.7%) then buffaloes (21.9%) and the lowest incidence was recorded in camels (8.8%). The rate of filarial infestation in camels, cattle and buffaloes was increased in summer and spring months (May, June , July , August and September) and decreased in winter and Autum. The infestation in summer and spring was (14.7% and 12.5%), (35.08% and 30.7%) and (39.1% and 21.6%) in camels, cattle and buffaloes respectively. The infestations of equine Setariosis was increased in summer and spring months (May, June, July, August and September) which was (18% and 9.3 %), (48% and 33.3 %) and (64.5 % and 35.6%) in horses, mules and donkeys respectively while infestation of Equine Onchocercosis was (52% and 37.2%), (66 % and 51.5%) and (94.9% and 71.2%) in these animals. The infestations of camels, cattle and buffaloes were increased in animal with age over 8 years which were 10.8%, 69.5% and 30.05% respectively, The infestations of equine Onchocercosis and Setariosis in age over 8 years were (53.7% and 13.01%) , (62.4% and 42.9%) and (96.8% and 54.3%) in horses, mules and donkeys respectively. The incidence of filariasis in male camels was higher than that in females. Also incidence of filariasis in female cattle and buffaloes was higher than male which was (58.1% and 30.3%) and (2.40% and 4.16%) in female and male cattle and buffaloes respectively. However the sex of equine was not affect the incidence of filariasis . The mainly clinical signs: 1. camels filariasis were edema in the hind legs, enlargement of scrotum, orchitis and respiratory distress. While filariasis 2. buffaloes was taken showed two clinical form, the ulcerative dermatitis which characterized by skin ulceration had no tendency to heal and edematous form in the legs. 3. Equine filariasis characterized by fistulous wither closed or open, conjunctivitis and keratoconjunctivitis with obstruction of nasolacremal duct and ulcerative dermatitis below the nasal canthus and dermatitis with alopecia and scaliness in many parts of the body specially legs, face and neck. Regarding the parasitological diagnosis it was found that the camels were infested with Dipetalonema evansi, cattle and buffaloes by Onchocerca species depending on the morphological characters and measurement of microfilariae. According to adult worm morphology and measurements and character of microfilariae, it was found that the equine were infested with Onchocerca cervicalis and Setaria equina species. Histopathological examination of tissue biopsies from the affected lesions showed the presence of tissue reaction in the form of cellular infiltration mainly eosinophils, mononuclear cells and plasma cells. Also in some section adult worms have been found surrounded by tissue reactions. Microfilariae were found numerous in section of infested skin. Evaluation of the diagnostic tests used for diagnosis of filariasis in examined animals, it was found that nuclepore filter technique was highly specific and highly sensitive reached 100%. Regarding to other tests specificity and sensitivity were (100% and 41.17%), (100% and 31.25%), (100% and 68.75%) and (75% & 100%) in wet blood film, stained thick blood film, concentration methods and EITB tests respectively. The results of the serological test (EITB) revealed that 30% (6 out of 20 cases) of non infested equine (false +ve), 15% (3 out 20 cases) of non infested bovine(false +ve), 95% (95 out of 100 cases) of infested equine (true +ve), and 80% (40 out of 50 cases) of infested bovine (true +ve). Positive band in equine filaraisis was at 30 KDa and the positive band in bovine filariasis was at 55 KDa.