A total of 2,714 methanol extracts of 1,677 plant species in 178 families were screened for nemastatic activity against Rhabditis sp. by 96-well microplate bioassay. The plant extracts with a concentration of 5,000 μg/ml were mixed with aqueous nematode solution containing about 20 Rhabditis sp. and their activity was examined daily for 7 days. Out of 2,714 plant extracts examined in this test, 2,362 (87.0%) showed no negative influence on the nematode activity, while 187 (6.9%) inhibited nematode activity about 50%, 95 (3.5%) inhibited nematode activity over 90%, and 70 (2.6%) rather enhanced nematode activity. Among those showing over 50% nemastatic activity, 25 extracts were randomly selected for further screening with Rhabditis sp. and with juveniles of Meloidogyne incognita. The screening revealed that 11 extracts (44%) were consistently nemastatic. The 282 extracts with nemastatic activity could be of use in future studies on nematicidal plants.