Thepaper studies the mechanical properties ofsteel fibers reinforced lightweight concrete.This kind of concrete is produced by usingscoria aggregateswhich can be found abundantly in Syria. Thelightweight concrete mixeswere designed for three different percentage of steel fibers (0, 0.5, 0.75)%. Different tests were performed to determine mechanical properties of product concrete such as compressive strength, elasticity modulus, splitting tensile strengthand flexural strengthalso; the stress–strain diagram of produced lightweight concrete was established under compression. The results showedanincrease of the compressive, splitting tensile and flexural strengths reach up 16.9%, 25.6%, and 53.6% respectivelywhen the steel fibers were used. Also the results indicated the importance of using the steel fibers to improve the performance of concrete and change its brittle behavior to ductile behavior.