The purpose of the study is to explore whether input enhancement as a subtype of FonF can be proven feasible and productive as part of normal classroom work and whether it can assist in learners` long-term progress in English. 80 freshmen who enrolled general English at a Korean university were divided into an experimental group and a control group and read the text in one of two conditions: no enhancement, relative-clause enhancement. The results demonstrated the translation task scores obviously showed the effect of input enhancement. The enhanced text of relative-clause led to learning relative-clause as a target linguistic structure. Second, the effect of relative-clause enhancement text was significant on reading comprehension test as well as on translation task. The interesting result was that the effects on relative-clause learning and reading comprehension were retained in the follow-up posttest conducted four weeks later. The study proposed that learners` linguistic developmental system have been affected by the enhanced relative-clause text generated by learners` need and that their interlanguage system be reconstructed.