The PT-91 Twardy ('Tough') is a Polish upgraded version of its T-72M1 tanks which includes both conversions of existing inventory as well as a number of new builds as well. This followed the successful conversion of older T-55AM tanks to Mérida standard during the 1980s. The most visually notable change was the incorporation of ERAWA reactive armor on the hull, turret, and the forward part of the new steel side skirts. There is also a new OBRA laser warning system which can be identified by four antennas around the turret and which is linked with the prominent Tellur smoke grenade dischargers of which 12 are clustered on each side. Electronics include a new computerized fire-control system with a passive image intensification sight, laser rangefinder, and two-axis stabilization for the main gun (which is unchanged from the original 2A46 125-mm smoothbore). Other features include an uprated engine and NBC protection system and the tracks now have rubber pads. Impressively, almost all the new or upgraded components are of Polish origin. The PT-91 entered Polish service in the early 90s and was also exported to Malaysia. More recently, the Polish government announced large numbers of its PT-91 fleet would be donated to Ukraine to resist the Russian invasion.

First prototype of the PT-91 was ready in 1992 and entered service shortly thereafter. Numerous development variants technology demonstrators have been built since, particularly for export some of which has been in collaboration with other countries such as Ukraine. The only export variant is the PT-91M Pendekar for Malaysia.