Objetivos:To compare Sonobreast?s malignancy detection accuracy in two separate groups of tumors: under and over 2cm. Metodologia: We collected 554 patient records with ultrasound detected tumors and calculated the risk of malignancy utilizing the Sonobreast software (a software that calculates the odds of a tumor being malign utilizing clinical and ultrasonographical data). Then, we compared the obtained result with the biopsy?s result (gold standard) for the two groups of tumors. Ultimately, we evaluated the test?s capability of detecting malignancy in both cases and compared them. Resultados: Analyzing the number of positive and negative results, according to size categories, we observed that tumor?s size influence on the Sonobreast result is not statistically significant (p-value=0.384). Conclusão: It was verified that the tumor?s size does not influence Sonobreast?s accuracy.