Leptospirosis is a zoonotic disease of worldwide significance in human being and many animals. This zoonotic disease causes infection in cats and other pet animals and these animals can influence human's health. This study have been performed for detection of sero- epidemiology of leptospirosis and evaluation of sero- prevalence of Leptospira serovars in both household and stray cats by Microscopic Agglutination Test (M.A.T). Serum samples of 71 cats in two household and stray groups (31 household cats and 40 stray cats) were collected. Specimens were examined through M.A.T, against antigens of serovars: canicola, grippotyphosa, icterohaemorrhagiae, pomona, hardjo, autumnalis, ballum. Only one of stray cats (2.5%) showed 1:100 (or more) serum- titer against Leptospira pomuna. The antibody titer was not observed against more than one serovar in any cats. Among the household cats, 6 of them showed suspicious titer (+2), which 5 cats had titer against grippotyphosa serovar and one cat against hardjo serovar. Among the stray cats 6 of them showed suspicious titer (+2), exactly same as household group. With attention to the lack of regular and annual vaccination of household and stray cats against these organisms, the results of this assessment are accurate. Fortunately, infection percentage at Tabriz is low in contrast of other part of Iran. It seems that lack of suitable conditions and climates for growing of these organisms is the most important preventive mechanism or Leptospirosis in cats is initially rare and appears to be mild although very little is known about the disease in this species.