The Gleason system for prostate cancer was based on a study of 270 patients from the Minneapolis Veterans Administration Hospital in 1966-1967. In 1974, Gleason and the Veterans Administrative Cooperative Urological Research Group expanded this study to 1032 men. These studies formed the basis of the Gleason grading system, which is now endorsed as the primary grading system for prostate cancer by the World Health Organization, the Armed Forces Institute of Pathology Fascicle on prostate cancer, the Association of Directors of Anatomic and Surgical Pathology, and the College of American Pathologists. In the nearly 40 years since its inception, several aspects about prostate cancer and its management have changed, most notably serum prostate-specific antigen, transrectal ultrasonography, 18-gauge needle biopsy sampling, immunohistochemistry for the diagnosis of cancer, and radical prostatectomy and radiation therapy as primary treatment modalities. Several aspects of the disease, and consequently the reporting needs, have changed such as reporting cancer on multiple cases in needle biopsies, multiple nodules in prostatectomy, tertiary patterns, variants and variations in prostate cancer. The application of the Gleason system, therefore, has varied considerably in contemporary surgical pathology practice. An International Consensus Conference attended by 80 urologic pathologists from 20 countries was convened to discuss clarifications and modifications to the Gleason system. This article serves as a brief overview and summary of the proceedings that have been published in detail in recent literature.