This study was conducted to evaluate the effect of mecoprop-wp concentrations on weed control, growth characters and yield in flax, after 7cm and 14cm of plant height it to the field. The major weeds were Alopecurus aequalis var. a murensis (kom) ohwi, Persicaria hydropiper spach, Lamium amplexicaule L, Stellaria alsine Grimm var. undulata ohwi, Eleusine indica(L.) Gaertn. Flax yield were increased somewhat more with 250g/10a mecoprop-wp at 7cm of plant height than the other treatment and by hand weeding treatment of mecoprop-wp, 250g/10a at 7cm of plant height was slightly harmful for the flax with recommended concentration, On the other hand, all treatments were harmful in the double dosage level.