Some forty twin seat MiG-21U's were delivered to the Bulgarian Air Force. This, 28, was one of the very last operational MiG-21s with that air force. On 18 December 2015, Bulgaria ceased operations with the type. Bulgarian operations with the MiG-21 spanned 52 years, with 226 examples in ten variants fielded between 1963 and 1990. In total, some forty of these MiG-21s were written off.