The onset of strain-induced crystn. of vulcanized natural rubber changed from 230% strain at 300 K to 280% strain at 343 K and to 340% strain at 383 K. The max. degrees of crystallinity of the samples were 3% and 1-2% at 343 K and 383 K, resp. The stress at max. elongation decreased from 5.4 MN/m2 at 300 K to 3.4 MN/m2 at 423 K. The retention of strain-induced crystallinity upon unloading was obsd. only for samples strained at 300 K and 343 K.