In the mid-1990s, commercial cultivation of transgenic insecticidal crops (Bt corn, cotton and potato) began in North America.  In 1998 and 1999, some researchers warned that these Bt crops may have unexpected negative effects on nontarget butterflies, beneficial natural enemy insects, and soil fauna.  Since then, many peer-reviewed articles have been published about the nontarget effects of transgenic insecticidal crops.  Most subsequent studies revealed that Bt corn pollen has no harmful effect on nontarget butterflies in the field.  Negative effects on predatory or parasitic insects shown in laboratory experiments have never been demonstrated in greenhouse or field studies.  Although assessing the effect on soil fauna is difficult compared with on nontarget butterflies or above-ground natural enemies, none of the reports have documented deleterious effects on soil biota.  The current commercially used Bt crops appear to have little significant adverse effect on nontarget fauna.  Before the approval of commercial field cultivation, many ecological risk assessments are imposed on new types of transgenic crops (new trait event) and the nontarget effect is an essential part of the risk assessment for transgenic insecticidal crops.  Many further articles on the nontarget effect will be published for transgenic insecticidal crops including the current Bt crops.