The paper presents a comparative study on mechanical properties of Neuropeltis acuminatas and Agave sisalana fibers reinforced plaster. The Neuropeltis acuminatas fibers have particular properties for the manufacturing of plaster matrix composite. Two types of composites architecture have been made of short and continuous fibers of different sizes. The composite materials were manufactured according to the following mixing ratio (by fibers content in the total weight of the manufactured composites): Plaster matrix composite samples with 0 %, 5 % and 10 % by weight of fibers contents. The composites were subjected to compression and three-point bending loadings. The modulus of elasticity, compressive strength and applied maximum force at break of the specimens were obtained by a previously established experimental procedure. Firstly, the results showed that reinforcing plaster with continuous sisal fibers offers the greatest performance during the compression loadings applied on the composite architecture, and the results showed that the mechanical characteristics of plaster matrix composite are improving with the orientation of continuous sisal fibers for different mixing ratio during three-point bending loadings.