A serological survey for detection of antibodies to leptospira spp. was conducted on stray and owned dogs serum. The samples were collected form different localities (rural, urban and suburban environmental) in Sharkia governorate, Egypt during the period from February, 2001 to March, 2003. A total of 290 dogs were tested by using ELISA and microscopic agglutination test (MAT) against six leptospiral serovars. At the time of blood collection, all the dogs appeared healthy with no clinical signs suggestive of leptospirosis. In addition, urine samples for bacteriological examination and paired serum samples for serological investigation were collected from 18 diseased dogs suspected to suffer from leptospirosis. Seroprevalence by ELISA was 12.4% (36/290) and by MAT was 10.7% (31/290). The most freqently serotypes identified serologically were Leptospira Canicola (38.7%) and L. Icterohae- morrhagiae (32.25%), followed by L. pomona (12.9%), L. Hardjo (9.7%) and L. Grippotyphosa (6.45%), while L. Sejroe antibodies were not detected. The prevalence in stray dogs was higher (13.9%, 12.1%) than in owned dogs (8%, 6.7%) by ELISA and MAT respectively. The seroprevalence in females was lesser than in males (P<0.05) and in puppies less than 1 year old it was lesser than in older animals (P<0.01). Four-fold rise in titers between serum samples obtained during the acute and convalescent phases were detected in three cases of diseased dogs and indicative to an acute leptospirosis. While, cultural isolation of leptospires from dogs urine was unsuccessful. It is concluded that, leptospirosis was of significant occurrence in stray and owned dogs in Sharkia governorate and consequently, dogs could be a reservoir source of infection to domestic animals and human.