The cure characteristics and mechanical properties of natural rubber filled with pineapple leaf fibre (PLF) were studied at different filler contents and particle sizes. The PLF was characterized for filler properties while carbon black (N330) served as the reference filler. The natural rubber vulcanizates were compounded on a two-roll mill. Results showed that PLF (300 μm) filled natural rubber vulcanizates exhibited the highest maximum torque (Tmax) (47.04 lb-in) at filler content, 10 phr among the filler particle sizes investigated. The minimum torque (Tmin) of the vulcanizates generally increased with the increase in filler contents and particle sizes. The scorch times of the rubber vulcanizates did not vary with fibre content while the cure times of PLF (300 μm) filled rubber vulcanizates decreased with filler content. The tensile strength (TS) of PLF (150 μm) filled natural rubber vulcanizates generally increased with the increase in filler content whereas the tensile modulus of the rubber vulcanizates decreased steadily with increasing filler particle size at filler contents, 5 and 30 phr. The elongation at break (EB) of the rubber vulcanizates exhibited no general order of variation with filler content and particle size, and was generally greater than that of unfilled natural rubber. The flexural strength of the rubber vulcanizates increased with increasing filler particle size at filler contents, 20 and 40 phr. The addition of PLF and carbon black improved the compression strength of the rubber vulcanizates, and which for PLF (300 μm) and CB fillers generally increased with the increase in filler content. The study has demonstrated the enhancement of properties of natural rubber vulcanizates on incorporation of PLF into natural rubber, however, the property enhancements obtained were less than those recorded for CB filled natural rubber vulcanizates.