Natural fibers could serve as viable and abundant alternatives to the expensive and non -renewable synthetic fibers as reinforcement in thermoplastic composites. The potentiality of banana stalk fiber at reinforcing a low density polyethylene matrix was examined in this study. Fibers were extracted from the stalk of banana plant and characterized for its chemical composition and fiber contents. The fibers were modified by pulping with caustic soda to increase it wettability. The fiber dimension was measured using a binocular light microscope. FTIR spectra was used to identify the functional groups of modified and unmodified fibers. The composites were produced using a single -screw extruder, pelletized and then processed into test specimen samples by injection molding. The fiber volume in the polymer matrix was varied from 5.4 to 20 %. The effects of chemical treatment and increasing fiber content on the moisture absorption and mechanical properties of the composites were examined. The results showed that fiber of banana plant were characterized by medium to long fiber length (2.84 mm). The lignin content (7.99 %) was relatively low indicating a lower value of chemical consumption in the modification step. The SEM micrograph of the composite cross section showed good fiber/matrix interfacial bonding. The water absorption capacity of the composites increased with increase in fiber loading while the treated fibers showed a reduction in hydrophylicity of the composites. The treated fibers showed improved tensile strength and can thus be utilized in the production of composites with better properties