Bird cherry-oat aphid, Rhopalosiphum padi (L.), a polyphagous species with a nearly worldwide distribution, is an important pest of wheat as well as the main vector of barley yellow dwarf virus. We evaluated the resistance categories of eight wheat lines including antibiosis, antixenosis, and tolerance against R. padi under laboratory conditions. The wheat lines tested were ERWYT 88-8, ERWYT 87-6, and ERWYT 87-4 (resistant); ERWYT 87-1, ERWYT 87-20, and ERWYT 88-11 (susceptible); ERWYT 88-12 and ERWYT 88-13 (intermediate). In the antibiosis experiment, R. padi produced fewest progeny on ERWYT 88-8, ERWYT 87-6, and ERWYT 87-4 in reproduction period. In the antixenosis test, R. padi performed best on ERWYT 87-1, ERWYT 87-20, and ERWYT 88-11. Fewer apterous aphids selected ERWYT 88-8, ERWYT 87-4, and ERWYT 87-6 lines indicating antixenosis of these lines to R. padi. In tolerance experiments, however growth parameters differed between treated and untreated seedlings of wheat lines with 10 aphids per day infestation during 21-d period, but not among eight wheat lines. The plant resistance index values were greatest for ERWYT 88-8 (9.71), followed by ERWYT 87-4 (7.04) and ERWYT 87-6 (4.76). ERWYT 88-8, ERWYT 87-6, and ERWYT 87-4 may be important sources of R. padi resistance for small grain breeding and integrated pest management programs.