Natural fiber has been developed as a composite reinforcing material. The development of natural fiber composites has been widely applied in various industrial fields such as automobile, shipping, transportation and biomedical industries. Abaca fiber is a type of natural fiber that has potential in the biomedical field because it has a high cellulose content. The purpose of this study was to determine the effect of the volume fraction of fibers with a matrix on the tensile strength of hybrid abaca / carbon / PMMA composites and determine the correlation of changes in the tensile strength values of abaca / carbon / PMMA composites. Abaca fiber was alkalized by soaking in 6% NaOH for 36 hours. Carbon fiber was soaked with liquid nitrogen for 10 minutes and cut into 10 mm pieces then mixed into PMMA with abaca:carbon ratio 1:1 and variation of volume fiber fraction and matrix 15%, 20%, 30%, 35%. Fabrication process is done white a cold press machine with a pressure of 4.37 MPa at room temperature for 60 minutes. All composite specimens were tested in accordance with ASTM D638-01 standards. After that, Scanning Electron Microcopy (SEM) was carried out on the fracture of specimens that had been tested for tensile. The result of this study is the tensile strength test result is affected by increasing volume fraction leading to an increas in interface fibers and matrix and the highest result is at 30% volume fraction white 121.28 Mpa and 6.10 GPa elastic modules. The result of SEM test in 30% volume fraction shows that fiber pull out in composite is detected because the fibers are fully mixed with PMMA matrix.