Abstract: The results of WAXD, SAXS and Laue photographs of 3,4-polyisoprene prepared under different condition and elongation ratio are presented. It is found that decrease of polymerization temperature increases the crystallinity of the polymer. Different nitrogen containing donors used as additive in the catalyst system fairely influence the crystallization of 3,4-PI.For the oriented samples, the degree of crystallinity and the values of long period increase, but the crystallite size decreases with increase of the elongation ratio.Some (hko) and one stronger (hkl) plane diffractions were obser-ved.It is concluded 3,4-PI belongs to the non-homogeneity particle system with parti-cle radius of 35—164Å.