Nowadays, kenaf fibers are becoming extensively used as natural reinforcements for polymeric composites. The mechanical properties of the fibers are the most influential elements on the characteristics of the composites. In the current work, tensile property of kenaf fiber was studied at different aging conditions (immersed in water, salt water, diesel, and engine oil). The tensile property of the fiber was tested in two different techniques as single fiber and bundle (2055 fibers). Surface morphology of the fibers, before and after aging, was observed using scanning electron microscopy. The results showed that engine oil highly influenced the mechanical properties of the fiber compared to the other solutions. A drop in the strength was about 70% for both untreated and treated fibers immersed in diesel solution followed by diesel, and then water. The reduction in tensile strength by saltwater solutions was the least, at about 27.16% for untreated fibers. The damage on the fiber aged in salt water was less than the damages observed on the aged fibers in other solutions.