Bamboo is an abundant material in Indonesia which has been previously studied as a construction material and reinforcement. The performance of concrete beam with knitted bamboo reinforcement are studied, especially on the flexural strength and crack behaviour. Three concrete beams with the dimension of 15 x 25 x 160 cm and three slices of bamboo in each knit are investigated. The outer skin surface of this knit is soaked NaOH with sikadur and sand as coating material. The results found that the flexural strength of concrete beam for the first and second model was 3.56 MPa and 6.15 MPa, respectively. Pure bending crack occurred on all concrete beam models.