(1) The resorcinol-hexa-silica bonding system is essential for NR-silk fiber systems. (2) Mechanical anisotropy is observable only at higher fiber loadings (20 phr and above) in NR-silk fiber systems. (3) In composites containing a sufficient amount of bonding agents and fibers for tensile anisotropy to be observed, tensile failure occurs by both fiber breakage and debonding. (4) Addition of silk fiber to NR causes (a) increase in hardness, (b) reduction in resilience and elongation at break, (c) increase in heat buildup and set, and (d) increase in tear resistance. (5) The aging resistance of silk fiber-reinforced NR composites is excellent only beyond a fiber loading of 20 phr. (6) Mill shrinkage and green strength of NR improve, while Mooney viscosity and scorch time increase with the addition of silk fiber to NR.