Fine needle aspiration biopsy cytology is part of the diagnostic triad in the evaluation of breast pathology, along with clinical and mammography or ultrasound findings. The Yokohama international system of the International Agency for Cytology has been proposed to report fine needle puncture-aspiration biopsy breast cytology, through 5 diagnostic categories: Inadequate/insufficient, benign, atypical, suspicious for malignancy and malignant, including in each of these definitions, key cytological diagnostic criteria and suggestions for clinical management. The objective of this article was to know the guidelines of this new breast cytological classification system for its implementation in this region. Fine needle puncture-aspiration biopsy is a precise and effective method to diagnose different breast lesions, which requires an adequate cell sample and a precise cytomorphological interpretation. The application of standardized Yokohama system will allow to improve the evaluation, diagnosis and clinical management of the breast pathology. Keywords: Breast cytology. Fine-needle aspiration biopsy (FNAB). Reporting system Yokohama.