Background and objective : In now Khon Kaen hospital have emergency patient increases, in some people wants to have diagnose that is correct and fast, then attending physicians have sending ultrasonography increase. To quantify the impact of ultrasonography (US) on the diagnosis and treatment of emergency conditions.Material and method : A prospective study was conducted between March  and December 2012 at a tertiary care hospital. US was performed by experienced staff radiologist during the working hours. Data collection forms were filled by experienced staff radiologists. The final discharge diagnoses were obtained from medical charts and computerized records. Data collected included age, gender, provisional diagnosis, ultrasound findings, the discharge diagnosis, time of ultrasound examination, other radiologic investigations and therapeutic interventions. Outcomes included the impact and diagnostic accuracy of US.Results : Three hundred sixty three patients underwent emergency ultrasound examinations. The median age was 46 years. Approximately 50% were male. The anatomical region most commonly examined was the abdomen (77%). US had an impact on clinical management in 94% of all examinations. The overall accuracy of US was 90%. Factors associated with higher impact included urological, vascular and musculoskeletal conditions, while less abdominal conditions were associated with less impact.Conclusion : The impact of US on the management of emergency conditions was high. However, a more efficient use of emergency US is still possible, especially for abdominal conditions.