This paper presents a numerical study of the lateral load-carrying capacity of hemp concrete as infill material in timber frame walls. The parameters that significantly affect the lateral resistance of hemp walls were investigated. For this purpose, vertical stud timber frame walls measuring 2.5 m in height and 1.2 m in length were used as the benchmark to validate earlier experimental work. A numerical study of three timber walls filled with hemp concrete was conducted to assess the effect of wall length on the lateral load-carrying capacity of hemp concrete. Three vertical stud timber frame walls with a standard height 2.5 m and different lengths (1.2 m, 1.6 m and 2.4 m) were investigated using Abaqus software. This study confirms, firstly, that the length of a timber wall plays a significant role in the lateral load-carrying capacity of hemp concrete. Secondly, the contact and bonding between the hemp concrete and timber wall have a significant effect on the lateral load-carrying capacity of hemp concrete as infill material in timber frame walls. It was clear, from the numerical results, that increasing the length of the wall significantly increases the contribution of hemp concrete to lateral resistance. Good contact and bonding between the hemp concrete and the timber elements also increase the lateral strength of the hemp wall.