It was clear even during the Spanish Civil War that the 37mm PaK 35/36 anti-tank gun was no longer sufficient to deal with modern armored vehicles. And so Germany began in 1938 to develop a new 50mm weapon, designated the PaK 38, that entered service in 1940.

The PaK 38 was mounted on a two-wheel carriage that used light alloys to reduce the weapon's overall weight. It was fitted with a castor wheel under the split trails, and the main wheels had a torsion bar suspension that locked when the trails were split for firing. It was also fitted with a gun shield that protected the crew from small arms fire and fragments. While it could be repositioned by the crew, it was normally towed by half-tracks or trucks.

Using the tungsten core anti-tank ammunition introduced in 1940, the PaK 38 could deal with most Allied tanks, and was the only weapon available that could penetrate the armor of the Soviet T-34.

Later in the war, the PaK 38 was fitted with an automatic feed and mounted in aircraft as a tank-buster; it was also later converted into an anti-aircraft gun (the 50mm Flak 214).

Although it was replaced in production by the more powerful 75mm PaK 40, the PaK 38 continued to serve on every front until war's end.