Abstract: Foerign language learners who just learn Indonesian will be surprised to see some Indonesian wordswhich are similar (Using the Some root), such as bertemu, menemukan, menemui, mempertemukan, pertemuan, penemuan, penemu, temuan, temui, temukan and ketemu. After knowing that the derived words consist of root and affixes, ussually the foreign language learners will do some ezperiment by making some other derived words. the result of the experiment indicates acceptable and unacceptable affixed words. Th acceptable affixed-words will cause positive impact to the learners and the unacceptable affixed words will cause negative impact.

key words: foreign language learners, affixed words, positive impact, negative impact.