5169 accessions of Amazon Hevea new germplasm were evaluated during 1986-1993 for cold tolerance by radiative low temperature treatment in the phytotron (PGV-36). 50 germplasms were screened out which were more cold tolerant than 93-114, the most cold-tolerant clone in China at present. Among them No. 241 AND No. 168 demonstrated tolerance to both advective and radiative cold damages, and 10 survived a cold treatment at a minimum temperature of -2 C for 15h, and 14 possessed more advantageous traits. It was proved that the simulated radiative cold damage gave a similar result to the cold damage in the field. The cold hardy germplasms evaluated would greatly enrich Hevea gene resources in our country and would provide valuable materials for breeding and selection and biotechnological studies of cold hardy Hevea clones.