L-39X-01 – X-07
Five prototypes plus two static test airframes.

L-39C (C for Cvičná – training)
Standard basic trainer for Soviet Union, Czechoslovakia and export.
Originally designated L-39, but renamed L-39C when later variants appeared.
Two pylons under wing.
Approximately 2,260 built.

L-39CM (CM for Cvičná modernizovaná – modernised training)
Slovak upgraded C version.

L-39M1
Ukrainian upgraded C version with AI-25TLSh engines.
The conversion is carried out by Odesaviaremservis and the first plane was ready in 2009.
The upgrade of a further 7 L-39C's was planned.
Only six L-39C were converted into L-39M1 by 2014
L-39V (V for Vlečná – tug)
Single-seat target tug version for Czechoslovakia.
Equipped to tow KT-04 target on 1,700 m (5,600 ft) cable.
Prototype plus eight production aircraft built.

L-39ZO (Z for Zbraně – weapons)
Interim weapon trainer variant for export.
Four pylons stressed for 500 kg (1,100 lb) (inboard) and 250 kg (550 lb) (outboard), with total external load of 1,150 kg (2,500 lb).
First flew 25 June 1975, with initial deliveries to Iraq in 1977.
337 built.

L-39ZA
Significantly upgraded L-39ZO for armed training and light attack, employing sturdier landing gear, a higher payload (total 1,290 kg (2,844 lb)) and notably provision for a GSh-23L 23-millimeter twin-barreled cannon attached in a conformal pod under the pilots' compartment, having a 150-round magazine within the airframe.
Outer pylons wired to carry K-13 or R-60 air-to-air missiles.
Two prototypes, with first flying on 29 September 1976.
208 aircraft delivered.

L-39ZAM
Slovak upgraded ZA version.

L-39ZA/ART
Thai version of L-39ZA with Elbit avionics.
40 built.

L-39MS/L-59
The Aero L-39MS is a second generation military trainer aircraft developed from the firm's earlier L-39.
Compared to its predecessor, it featured a strengthened fuselage, longer nose, a vastly updated cockpit, and a more powerful (21.6 kN (4,850 lbf)) Lotarev DV-2 engine, allowing operation at higher weights and speeds (max speed 872 km/h (542 mph)).
First flight on 30 September 1986.
It was later designated as the Aero L-59.

L-139 Albatros 2000
Revised version with western avionics and 17.99 kN (4,045 lbf) Garrett TFE731-4-1T engine.
Single prototype built.

L-159
Further modernised advanced trainer/combat aircraft with more modern, western avionics and Honeywell/ITEC F124 engine.

L-39NG
Modernised and upgraded version with Williams FJ44 engine, improved fuel system and avionics, planned to be introduced in 2018.

Skyleader UL-39 Albi
A carbon-fibre ducted-fan powered scale variant first flown in the Czech Republic on 4 April 2016.
L-39X-01 – X-07
Five prototypes plus two static test airframes.
L-39C (C for Cvičná – training)
Standard basic trainer for Soviet Union, Czechoslovakia and export. Originally designated L-39, but renamed L-39C when later variants appeared. Two pylons under wing. Approximately 2,260 built.
L-39CM (CM for Cvičná modernizovaná – modernised training)
Slovak upgraded C version.
L-39M1
Ukrainian upgraded C version with AI-25TLSh engines. The conversion is carried out by Odesaviaremservis and the first plane was ready in 2009. The upgrade of a further 7 L-39C's was planned. Only six L-39C were converted into L-39M1 by 2014
L-39V (V for Vlečná – tug)
Single-seat target tug version for Czechoslovakia. Equipped to tow KT-04 target on 1,700 m (5,600 ft) cable. Prototype plus eight production aircraft built.
L-39ZO (Z for Zbraně – weapons)
Interim weapon trainer variant for export. Four pylons stressed for 500 kg (1,100 lb) (inboard) and 250 kg (550 lb) (outboard), with total external load of 1,150 kg (2,500 lb). First flew 25 June 1975, with initial deliveries to Iraq in 1977. 337 built.
L-39ZA
Significantly upgraded L-39ZO for armed training and light attack, employing sturdier landing gear, a higher payload (total 1,290 kg (2,844 lb)) and notably provision for a GSh-23L 23-millimeter twin-barreled cannon attached in a conformal pod under the pilots' compartment, having a 150-round magazine within the airframe. Outer pylons wired to carry K-13 or R-60 air-to-air missiles. Two prototypes, with first flying on 29 September 1976. 208 aircraft delivered.
L-39ZAM
Slovak upgraded ZA version.
L-39ZA/ART
Thai version of L-39ZA with Elbit avionics. 40 built.
L-39MS/L-59
The Aero L-39MS is a second generation military trainer aircraft developed from the firm's earlier L-39. Compared to its predecessor, it featured a strengthened fuselage, longer nose, a vastly updated cockpit, and a more powerful (21.6 kN (4,850 lbf)) Lotarev DV-2 engine, allowing operation at higher weights and speeds (max speed 872 km/h (542 mph)). First flight on 30 September 1986. It was later designated as the Aero L-59.
L-139 Albatros 2000
Revised version with western avionics and 17.99 kN (4,045 lbf) Garrett TFE731-4-1T engine. Single prototype built.
L-159
Further modernised advanced trainer/combat aircraft with more modern, western avionics and Honeywell/ITEC F124 engine.
L-39NG
Modernised and upgraded version with Williams FJ44 engine, improved fuel system and avionics, planned to be introduced in 2018.
Skyleader UL-39 Albi
A carbon-fibre ducted-fan powered scale variant first flown in the Czech Republic on 4 April 2016.
Aero L-39 Albatros