Release strain measurements were conducted on the aerial roots of Ficus elastica Roxb. to understand stress generation in roots. Regardless of whether the roots are small roots that are directly attached to the ground (Type I), small roots that have merged with other roots without reaching the ground (Type II), or large roots that are directly attached to the ground (Type III), all gave negative strain values indicating that they were under tensile stress prior to measurements. Such strains were inversely affected by the strain gauge distance from the root attachment (either to the ground or to other roots) and by the root diameter. Tensile stresses emanated from the gelatinous fibers found near the pith of the roots.