Abstract
Objective
To determine which of four modalities of English lexical knowledge (active recall, active recognition, passive recall and passive recognition), was the most difficult for learners to use in terms of the meaning among Irani students.
Methodology
This descriptive study was carried out with participation of 134 students of Medical Sciences University of Tabriz. Four vocabulary size tests based on Laufer and Goldstein Vocabulary Knowledge Test were used to estimate the strength meaning of four aspects of English vocabulary knowledge. In preparing tests," 3000 Most Commonly Used Words list in the English Language (USA)" was used. The validity and the reliability of the self-constructed questionnaires were confirmed. Data analysis was performed using SPSS Software.
Results
There were 60.4% female and 32.8% male participants; 68.7% were Turkish, 12.7% Kurdish and 18.6% Persian. The mean value of the active recall test was 17.01+5.50, passive recall was 19.25+4.97, active recognition was 20.59+ 4.29 and passive recognition was 21.62+4.19. According to the hierarchal degree of difficulty, the most difficult modality was found as active recall and the easiest one was passive recognition.

Conclusion
As the active recall modality was the most difficult one, the methodology of vocabulary teaching would be more useful by putting the main focus on productive way of teaching. The study also provides clues in preparing class quizzes, mid-term exams and final evaluations. Syllabi for General English should be written according to the students' pedagogical needs as well. (Rawal Med J 2011;36:310-313).

Key words: English Lexical knowledge, active recall, active recognition, passive recall, passive recognition