INTRODUCTION. Ultrasound is essential in emergency medicine. However, learning curve to obtain technical and operative is unknown. ACEP suggests a minimum of 25 repeats by every ultrasound window. This study evaluated learning curve for ultrasound window of Inferior Vena Cava (IVC). AIM: To establish learning curve in emergencies medical residents needed to obtain a proportion of success above 80% in ultrasound window for IVC, measured by ACEP scale for quality assurance. METHODS: An experimental non-comparative study was designed to evaluate the success proportion of IVC ultrasound window after repetitive attempts. An expositive class of the technique was made prior to the experiment. Videos were assessed based on ACEP scales. For statistical analysis a multilevel logistic model was used for success proportion grouped by data and subject. RESULTS: Data were obtained from 8 residents. Each one made 25 repeats to 3 randomized healthy models. Learning curve adjusted by subject and number of repeats showed a proportion of 0.81 (range from 0.57 to 0.93) after 11 repeats and 0.9 (0.75 to 0.96) after 21 repeats. CONCLUSION: For a success proportion of 80 and 90% in IVC ultrasound window, 11 and 21 repeats are needed, respectively.