||This study evaluated responses by migratory spawning-phase sea lampreys Petromyzon marinus to artificial trap lighting in the laboratory and field with the aim of improving trapping as a method of sea lamprey control in the Laurentian Great Lakes. We hypothesized that lighting would improve trap success by increasing the attraction to, entrance into, or retention within portable sea lamprey traps. The responses of migratory sea lampreys to nocturnal lighting were complex and situation dependent. In the laboratory, where two traps were placed side by side, more sea lampreys were caught in the lit trap than in the unlit trap (80% versus 20%), largely because of increased attraction to the lit trap (75% of trap funnel entries by sea lampreys were in lit traps). In the field, where two traps were set 9 m apart and located against a barrier to upstream movement, there was no consistent difference in the numbers of sea lampreys caught in lit versus unlit traps. We provide two hypotheses for the variability in response to trap lighting between the laboratory and field, but overall the inconsistency of sea lamprey response to trap lighting leads us to conclude that the benefits of implementing trap lighting for sea lamprey control are limited. Lighting traps may be beneficial in situations where lighting is implemented in conjunction with other trap modifications that attract sea lampreys to within close proximity of traps or when traps are operated in stream locations that already encounter high volumes of sea lampreys.