Cholera is a disease with acute diarrhea caused by vibrio cholera which it’s serogroups O₁ is more responsible for several epidemy in numerous countries . There are two biotypes classic and eltor that has three serotypes ogawa , inaba and hikojima . This survey with beginning cholera epidemy in Hamadan was performed
   with aim to investigation etiology , clinical manifestation and laboratory findings in referred patients to health services in Hamadan province.

          The method of survey was descriptive cross-sectional research and were done in summer and autumn 1998. We described all of patients with acute diarrhea that were done culture from rectal swabs in TCBS (thiosulfate citrate bile salts sucrose agar) medium. From 718 positive cultures one hundred culture were chosen
   randomly and antibiogram test was performed for 10 current antibiotics.

          From 27380 patients were done rectal swabs in TCBS medium that 718 cases (2.6%) were positive culture which all of identified vibrio cholera seogroup O₁(with Eltor biotype and ogawa serotype). The patients were 50.6% male and 49.4% female. The most frequency in 20-29 years and 10-19 years age groups were 22.7% 17.7% respectively. The most frequency of cholera was seen in months August and September 65% and 28.5% respectively. The patients were admitted in hospital 18% cases and 82% cases were treated out patient. In the admitted patients(129 cases) had afebrile 95.3% , rice watery diarrhea 94.6% , vomiting 68.2% , abdominal pain 45.7%. Laboratory findings were leukocytosis 77.5% , hypokalemia 61.9%. WBC 21.7%  and RBC10.1% was reported in stool examination. In antibiogram the most resistancy
   was reported to co-trimoxazole and furazolidone 99% and 98% respectively and most sensitivity to ciprofloxacine , nalidixic acid , tubromycin , doxycyline was reported 99% , 98% , 93% , 85% respectively. 5 cases (0.7%) were died due to acute renal failure.

          Leukocytosis , WBC and RBC in stool examination of some patients showed co- infection with other invasive intestinal pathogens or new serotypes of vibrio cholera. So we recommend that in epidemy of cholera , stool culture should be done for others pathogens and serotyping of all of isolate vibrio cholera.