In 1940 the Bulgarian Air Force received 19 Me-109E-4's. In 1943 there were further deliveries of G-2's, G-4's and G-6's. 

In 1944 Bulgaria switched sides and joined the Allies. The 109's of the Bulgarian Air Force fought against the Germans. After the war the Bulgarians received more than 100 G-10, G-12 and G-14 airframes found in Austria. A number of these were sent to Yugoslavia as war reparations. In Bulgaria the 109 was withdrawn from service in 1946.

When the Bulgarian Air Force was formed in 1937 the aircraft carried an insignia based on the royal coat of arms. When Bulgaria joined the Axis powers in 1941 a black diagonal cross on a white square shield was selected. In 1944 when the Bulgarians switched sides and a white and red roundel with a green horizontal bar was carried.

On the fuselage of this Me-109E-4 you can see the royal roundel used before the black cross. The old insignia were overpainted with the new. (Source: Sojusznicy Luftwaffe Bulgaria)

Me-109 G-6 in 1944 (Source: Sojusznicy Luftwaffe Bulgaria)

Me-109 G-5 (Source: Wings of Fame 11)

Me-109 G-6 carrying the post 1944 roundels (Source: AJ Press Monografie 50: Messerschmitt Me-109 Cz. 6)

Me-109 G-6 (Source: Sojusznicy Luftwaffe Cz. 1)

Me-109 G-6 carrying the post 1944 roundels (Source: AJ Press Monografie 50: Messerschmitt Me-109 Cz. 6)

Me-109E-4 with the pre 1941 insignia (Source: Sojusznicy Luftwaffe Bulgaria)

The same Me-109E-4 with the post 1941 insignia (Source: Sojusznicy Luftwaffe Bulgaria)

Me-109 G-2 (Source: Sojusznicy Luftwaffe Cz. 1)