Strain-induced crystallization (SIC) was studied in blends of cis-l,4-polyisoprene (hevea rubber) and synthetic trans-1,4-polyisoprene (t-PI) using the wide-angle x-ray scattering technique. Uncrosslinked solution blends were uniaxially stretched at room temperature, and the dependence of the apparent crystallinity on elongation and t-PI content was analyzed. With increasing amounts of t-PI, both the onset of SIC phenomenon and the rupture occur at smaller elongations. These results are in accord with those obtained previously on true stress and birefringence.