A semiconductor memory device may include a semiconductor substrate with an active region extending in a first direction parallel with respect to a surface of the semiconductor substrate. A pillar may extend from the active region in a direction perpendicular with respect to the surface of the semiconductor substrate with the pillar including a channel region on a sidewall thereof. A gate insulating layer may surround a sidewall of the pillar, and a word line may extend in a second direction parallel with respect to the surface of the semiconductor substrate. Moreover, the first and second directions may be different, and the word line may surround the sidewall of the pillar so that the gate insulating layer is between the word line and the pillar. A contact plug may be electrically connected to the active region and spaced apart from the word line, and a bit line may be electrically connected to the active region through the contact plug with the plurality of bit lines extending in the first direction. Related methods are also discussed.