The study was carried out to determine the physical and mechanical properties of composite lumber made from cassava (Mahinot esculenta Crantz) and bamboo (Bambusa vulgaris) in different ratios which is 100% cassava with 0% bamboo, 75% cassava with 25% bamboo, 50% cassava with 50% bamboo, 25% cassava with 75% bamboo and 0% cassava with 100% bamboo. The tests samples for determining the strength properties were divided into two categories namely mechanical testing and physical testing. Basic density of the samples was carried out for physical testing. The lowest basic density was in samples with 100% cassava which is 0.49 g/cm3 and highest in samples with 100% bamboo which is 0.68 g/cm3. Two tests for the mechanical testing are bending test and compression test. In bending test, modulus of elasticity (MOE) and modulus of rupture (MOR) were both highest for samples with 100% bamboo which the reading of MOE was 16794.03 N/mm2 and 122.52 N/mm2 for MOR. Similar to the bending test, compression test is the highest for the samples with 100% bamboo which are 65.58 N/mm2. From statistical analysis, the basic density, static bending can compression strength give significant value at 95% confidence interval.