PT-91 “坚韧”型坦克（波兰语：Twardy）是一种波兰制主战坦克。它是T-72M1型主战坦克的改进型，最早于1995年服役。PT-91是由OBRUM（OBRUM是波兰语Ośrodek Badawczo-Rozwojowy Urządzeń Mechanicznych的缩写，意为机械设备研发中心），并由Bumar Łabędy公司生产，后者是波兰军事财团Bumar Group的一部分。相比T-72，PT-91加装了一套新型双轴稳定火控系统、反应装甲、一台动力更强的发动机、传动系统和新型自动装弹机。与其他许多T-72改进型不同，波兰陆军的PT-91在升级中所使用的部件几乎全部是本国企业制造的（包括新型发动机、火控系统和所有通信系统组件）。这些部件中有许多都被用于为其他国家升级其现有的T-72坦克，比如捷克的T-72M4Cz、格鲁吉亚的T-72SIM-1和印度的T-72 Ajeya Mk2。

The PT-91 Twardy ("hard","tough" or "resilient") is a Polish main battle tank. It is a development of the T-72M1 and first entered service in 1995. The PT-91 was designed at the OBRUM (OBRUM for Ośrodek Badawczo-Rozwojowy Urządzeń Mechanicznych – Polish for Research and Development Centre for Mechanical Appliances) and is produced by the Bumar Łabędy company – part of Polish military consortium – Bumar Group. Changes from the T-72 include a new dual-axis stabilized fire-control system, reactive armour, a more powerful engine, transmission and new automatic loader. Unlike many other T-72 upgrades the Polish Army PT-91s are upgraded using elements created almost exclusively by domestic companies (this includes new engine, fire control system and all communication system elements). Many of those elements were used to upgrade existing fleets of T-72 tanks in countries like in Czech Republic – T-72M4 CZ, Georgia – T-72SIM-1 or India – T-72 Ajeya Mk2.