The search for new composites that use natural fibers as reinforcement has driven the study of the vegetal fibers they are renewable, biodegradable, low cost and cause low environmental impact. Licuri fiber is obtained from the leaves of the Syagrus Coronata palm tree and possesses sufficient malleability to be woven. However, this type of material is subject to changes in mechanical behavior as a consequence of the natural degradation, mainly to those due to moisture absorption that can cause irreversible structural damage. In this sense, the present work sought to make an analysis of the influence of moisture on the mechanical performance of a unidirectional composite laminate of polyester matrix reinforced with licuri fibers. The composite laminates were manufactured by the by hand lay-up process. Water absorption, Uniaxial tensile and Three-point bending tests were perfomed according to ASTM D 570-98, ASTM D 3039-08 and ASTM D 790-07 standards, respectively. The results obtained on tests with composite in saturated state when compared to the tests with composite in the dry state (literature data) have shown that the polyester matrix composite reinforced with natural licuri fibers has its mechanical properties reduced by around 27% when exposed to moisture, as a confirmation of the hydrophilic nature of plant fibers.