The use of natural materials from renewable sources has several advantages when compared with non-renewable materials. Among these, there are vegetable fibers and sisal fibers that highlight for its wide application. Natural fibers appear as an alternative reinforcement to synthetic fibers, reducing costs and showing results close to synthetic fibers. The use of fibers is still growing slowly, but is already used in internal components of popular cars, elevator aircraft and structural components of the shipbuilding industry. In this article were produced composites reinforced by sisal fibers under two conditions: in a form of chopped fiber at a random disposition, and long and aligned fibers. In the first condition, sisal fibers were chopped in a granulator mill with length varying between 5mm to 15mm and randomly arranged in the polymeric matrix. In the second condition, the sisal fibers were arranged in an orderly manner and aligned in one-way direction. The results showed that the composite sisal with greater mass fraction showed better tensile stress in the case of random and particulate fibers. However, the results of the laminated composite reinforced by aligned and long sisal fibers, proved better results than particulate composites. This paper presents other results from literature and ends with a microstructural analysis of sisal fiber without chemical treatment.