Coating mortars should be capable of absorbing small deformations to ensure masonry stability (performance and durability). When this premise is not met, there is a greater propensity for the appearance of cracks, one of the major and worrying pathological manifestations in mortar coatings. One of the alternatives to combat this pathological manifestation is the addition of natural/artificial fibers in order to improve the mechanical properties (mainly the tensile strength) and, consequently, the deformation capacity of the mortars. In this perspective, this work analyzed the behavior in the fresh and hardened state of mortar with addition of fibers obtained from the carnauba straw (Copernicia prunifera), an abundant tree in the region of the Açu/RN valley. In order to achieve this goal, mortars were produced in a mass ratio of 1:3 (cement:aggregate) with addition of 3% and 5% of the carnauba straw fiber in relation to the cement mass and with water/cement ratio(a/c) fixed at 0,72 for all mixtures. The fiber lengths were further varied by 20, 40 and 60 mm. The properties of the mortars were evaluated in the fresh state (consistency) and hardened (compressive strength and flexural tensile strength). The results indicated that the addition of fibers of the carnauba straw results in mortar with less consistency and lower mechanical resistance. However, the best performance was obtained when 3% fiber was added and 60mm length was used.