Placement of an external support has been reported to prevent intimal hyperplasia of vein grafts. In this study, we investigated the effect of HA/CMC on intimal hyperplasia in a rabbit model. Right jugular vein to common carotid artery bypass grafting was performed in 24 female New Zealand white rabbits (2.5–3.0 kg). Animals were divided into two groups: control group (n=12) and HA/CMC group (n=12). Absorbable membrane barrier was wrapped around vein grafts in HA/CMC group. In control group, no material was applied following venous graft bypass. At 1 month, in the vein grafts supported with the HA/CMC membrane neointimal thickening was significantly less (109 µm [IQR, 78–166]) compared to the unsupported control grafts (220 µm [IQR; 101–312]; p<0.001). Medial thickening in the HA/CMC group (128 µm [IQR, 101–181]) compared to unsheathed control grafts (182 µm [IQR, 131–255] p<0.001) was also significantly less. Periadventitial placement of HA/CMC as an absorbable membrane inhibits intimal hyperplasia of vein bypass grafts in a rabbit model.