The Slovak Š-328s carried out reconnaissance and bombing sorties in support of the Slovak participation in the Invasion of Poland in September 1939. Following Slovakia's participation in the German Invasion of the Soviet Union in 1941, Slovak Š-328s were used for patrol and reconnaissance flights and a few of them also attacked soviet trucks and cars. They were again used in anti-partisan operations in western Ukraine in the summer of 1942. At least 11 Slovakian aircraft were seized by Slovak insurgents and flown against the Germans in late 1944 during the Slovak National Uprising in September to October 1944. The unit never had more than three aircraft operational at time, but they were an important asset. On 7 September 1944, this aircraft achieved one of the last downings of an enemy aircraft achieved by a biplane, when a patrolling Š-328 was attacked by a reconnaissance Focke-Wulf Fw 189. The Fw 189 was damaged by machine gun fire and forced to land in an area controlled by the insurgents.