nowadays almost one seventh of people all over the world speak in "English" and numerous of the rest, learn it as a second or foreign language. Teaching and learning of this language is very important from political, social, cultural, scientific and international point of view. So, English as a subject has been embedded in curriculum of many formal educational systems. Teaching English in the formal educational system of Iran is started from guidance school and continued until pre-university. Word learning has an important role in foreign language learning process, because most of differences among languages refer to their word domain and many of them as Persian and English have very similarities in grammar domain. Learners to learn words for a long time may use many strategies that rehearsal (or rote memorization) seems to be the most prevalent of them. But, research has shown that this strategy is not so effective. Hence, researchers have examined more effective strategies such as mnemonic devices, for example keyword and mental imagery that effectiveness of them has been proved many times in different countries. The aim of this research is to examine the effectiveness of these two strategies in learning and retention of meaning of the English words in comparison to rote memorization among Guidance school pupils.