Three field experiments were conducted during 1998-99, 1999­2000 and 2000-2001 seasons at Sakha Agricultural Research Station, Kafr El-Sheikh, Egypt to investigate the effect of some weed control treatments on dodder control and flax productivity and estimate yield losses of flax due to dodder parasitism. The experimental site was artifi­cially infested with dodder seeds. Data revealed the effectiveness of some weed control treatments against dodder in flax fields. These treatments were butralin (48%) at 2.5 Llfed. (either soil incorporated or surface applied); imadazolinone (18%) at 0.40 L/fed. (applied twice); butralin at 2 L/fed. (soil incorpo­rated); and imadazolinone at 0.40 L/fed. (applied once). These treat­ments did not show any adverse effect on flax, but on the contrary they increased plant height, biological and seed yield of flax. Hand weeding (twice) was not effective againest dodder during the three seasons of study, where, it reduced dodder population by 45, 46 and 23%, respec­tively. Data revealed that dodder parasitism decreased plant height sig­nificantly. Also, it reduced the biological yield by 1.86 and 1.57 t/ fed. and reduced seed yield by 0.57 and 0.62 t/fed., respectively during 1998/99 and 2000/2001 seasons as compared with the non-infested plots.