To study the resistance of alfalfa to alfalfa weevil, 124 Iranian and introduced alfalfa varieties and lines were studied in three field and one greenhouse - experiment (s). Traits studied were amount of damage to the plants, rate of insects on the plants, plantheight,flowering time, dry yield and cytological situation of the varieties. The results showed that some resistant varieties have the resistance mechanisms of tolerance, however, some other may have mechanisms such as antibiosis or non—preference, or a combination of both.
)