The Executive Regulation of the Prisons and Security and Correctional Measures Organization of Iran (2021), aimed at enhancing the prison system, dedicates Articles 22-36 to the classification and segregation of prisoners based on age, gender, type of crime and dangerousness. This study examines the compliance of these articles with Rule 11 of the Nelson Mandela Rules (2015), which emphasizes appropriate prisoner segregation. The research adopts a descriptive-analytical method with a comparative approach. Findings indicate that the 2021 Regulation, by establishing a Classification Council, segregating youths aged 18-25, political prisoners and limiting the detention of dangerous prisoners to 15 days, takes significant steps toward global standards. These provisions are more advanced than the 1384 Regulation and align with Article 514 of the Criminal Procedure Code (2013). However, overcrowding, insufficient space and inefficient technological infrastructure hinder full implementation. The lack of independent oversight further weakens compliance with Rule 84 of the Nelson Mandela Rules. The study recommends reducing overcrowding through alternative punishments, enhancing infrastructure and establishing independent monitoring bodies to improve alignment with global standards. This research underscores the importance of classification systems in rehabilitation and harm reduction, offering solutions to overcome implementation barriers.