This paper presents an investigation of the flexural behaviour of reinforced lightweight concrete beams made from lightweight expanded clay aggregate (LECA). Nine reinforced concrete beams were fabricated and tested using the symmetrical two-point loads test. The concrete strength and steel bar reinforcement were two important parameters examined during the beam tests. The paper compares flexural performance of the tested beams for example failure modes, load deflection response, and ultimate moment capacity with those of the theoretical analysis. The experimental results suggest that the ultimate moment of beams made with LECA lightweight concrete could be predicted satisfactorily using the equation provided by the ACI 318 building code. However, the maximum section bars for restraining brittle compression failure should be reduced in the beams. Key words: Lightweight concrete, reinforced concrete beam, flexural behaviour, failure mode, ultimate moment.