The aim of this research is using latex from para-rubber mixed in concrete block to develop strength and thermal insulation properties. The concrete blocks are formed under TIS standard . The compressive strength and water absorption are tested by TIS standard  while the bending strength and coefficient of thermal conductivity are evaluated by ASTM standard [2, 3]. From the results, the water absorption of concrete block is reduced. When the latex to cement ratio is increased, the bending strength increases while the compressive strength decreases. For the insulation property, it indicates that the concrete blocks with para-rubber is an excellent insulation. This means latex from para-rubber could be an admixture which improves concrete block properties for strength and thermal insulation.