Acute diarrhoea in adults is one of the most commonly encountered medical emergency in general practice and is responsible for considerable morbidity around the world. To evaluate the efficacy and tolerability of fixed dose combination of ofloxacin with ornidazole infusion (infusion O2) in the management of diarrhoea and dysentery, a study was carried out among 290 patients, age group from 18 to 65 years suffering from diarrhoea, dysentery, gastro-enteritis. Study drug infusion O2, (Medley Pharmaceutical, Mumbai) containing ofloxacin 200 mg + ornidazole 500 mg was administrated twice daily for a duration of 5 days. Number of soft or watery stool, body temperature, nausea, abdominal pain, gas and flatulence were recorded at baseline and at the end of the study. Tolerability and efficacy was evaluated based on the global assessment by the investigator based on a 3-point scale marked as excellent/good/poor. Two hundred and fifty-six-patients (160 male and 96 female) were included for final analysis, 34 patients lost to follow-up. Mean number of watery stool per day was reduced from 9.273 +/- 0.4537 to 1.375 +/- 0.07001 (p < 0.0001) by infusion O2. Body temperature was significantly reduced from 38.055 +/- 0.045 degrees C to 36.778 +/- 0.016 degrees C (p < 0.0001) at the end of the study. Pretreatment symptom nausea was significantly reduced in 90.34% of patients. Improvement in vomiting symptoms was reported in 72.35% of patients after administration of anti-emetic drug; 96.84% and 77.25% of patients reported improvement in abdominal pain and gas/flatulence respectively at the end of the trial by infusion O2. As per investigators' assessment about efficacy of trial drug, 98.43% of patients reported good to excellent and 1.56% reported poor efficacy. As per investigators' assessment about tolerability 98.43% of patients reported good to excellent and 1.17% reported poor tolerability. Minor incidences of nausea, gastritis, metallic taste were reported in 7.42%, 7.14%, and 5.85% of patients respectively. No serious adverse events were reported which led to withdrawal of patient from the study. Result of this study shows that, combination of ofloxacin with ornidazole infusion (infusion O2) significantly reduces number of watery stool and associated symptoms like nausea, abdominal pain, flatulence/gas with excellent tolerability.