Objective: The objective of this study was to validate the SONOBREAST statistical model in women at a private clinic with a different epidemiological profile from those in the initial study. Materials and Methods: This is a study to evaluate the performance of a diagnostic test (SONOBREAST) and evaluated 500 breast nodules identified on ultrasonography. Surgery was indicated in all cases. The ultrasonographic characteristics, patients’ age, and family history of breast cancer were analyzed. The probability of malignancy was calculated according to the SONOBREAST model (www.sonobreast.com.br). The results were compared with the pathology findings. Results: A total of 274 women with a mean age of 41.92 ± 14.40 years were included. Overall, 86 (17.2%) tumors were malignant and 414 (82.8%) were benign, with 382 (76.4%) being non-palpable. The mean size of the lesions was 16.34 ± 8.73 mm. The sensitivity of SONOBREAST was 95.40%, specificity 78.69%, and accuracy 81.60%, with a positive predictive value (PPV) of 48.54% and a negative predictive value (NPV) of 98.78%. Conclusion: This study validates the use of SONOBREAST to evaluate the probability of malignancy in solid breast nodules identified on ultrasonography in women consulting at a private clinic.