This study is a follow-up of Hwang's (2007) empirical study, which investigated the role of awareness in Korean high school students' subsequent learning of the English passive. Hwang (2007) found the positive relationship between awareness and subsequent processing of the target structure and claimed the crucial role of awareness in successful second language learning. The present study explores whether the effects of awareness retain six months after the first post-exposure task of Hwang (2007), which was performed one day after the instruction. The results of the present study revealed the retention of the effects of awareness in the written production task as well as in the multiple-choice recognition task. However, no significant differences were found between the passive group, who were consciously aware of the target structure through a reading text and brief explanation about the English passive, and the preposition group whose attention could be implicitly drawn to the target structure through the reading text only. The results cannot fully support Schmidt's noticing hypothesis and can also be interpreted as providing evidence for the dissociation claim that L2 learning can take place implicitly without conscious awareness.