Recently, the authors have published studies focused on the echogenicity index analyzed in ultrasound B-images using own software designed to analysis of ultrasound B-images, developed since 2012. The studies have been focused on selected brain structures and the echogenicity index was firstly used in analysis of atherosclerotic plaques using B-imaging. The almost perfect reproducibility between two blind observers was confirmed. In this study focused on B-imaging of the thyroid gland, the authors analyze the reproducibility of the echogenicity index in a free-hand Region of Interest of the thyroid gland tumor. Overall, 102 images were processed. Both of the observers are non-experienced in sonography; the main goal of this study is to ascertain the level of agreement between results when the same ROI is used. The results repeatedly ascertained the almost perfect level of agreement of the echogenicity index for ultrasound B-images analysis in different structures. The correlation coefficient r=0.98 and the average absolute error between echogenicity index values is under 15 %. In this phase, the clinical point of view is not evaluated; only the reproducibility of the echogenicity index is judged. The echogenicity index will be analyzed to see if there is any relation between the echogenicity index and tumor type. All achieved results will be checked by an experienced sonographer for future clinical studies