Carotid angioplasty and stenting have developed into reliable options for patients with carotid stenosis. However, postoperative restenosis remains a serious and unresolved problem. Restenosis is partly caused by the proliferation of vascular smooth muscle cells. As certain long non-coding RNAs (lncRNAs) affect cell proliferation and migration, the present study aimed to investigate them as novel biomarkers for restenosis development and to further reveal the potential underlying mechanisms. The expression of lncRNA small nucleolar RNA host gene 1 (SNHG1) and microRNA145 (miR-145) in human carotid artery smooth muscle cells (hHCtASMCs) was analyzed using reverse transcription-quantitative PCR. In addition, a luciferase reporter assay was performed to investigate the interaction between SNHG1 and miR-145. The effects of the SNHG1/miR-145 axis on the proliferation and migration of hHCtASMCs were evaluated by Cell Counting Kit-8 and Transwell assays. Serum SNHG1 and miR-145 expression levels were increased and decreased, respectively, in patients with restenosis (all P<0.001). High SNHG1 and low miR-145 were identified as risk factors for restenosis onset (all P<0.01). Furthermore, decreasing SNHG1 expression levels in hHCtASMCs inhibited cell proliferation and migration. The luciferase reporter assay and expression results demonstrated that miR-145 may be a target of SNHG1 and mediated the effects of SNHG1 on hHCtASMC proliferation and migration. The results obtained suggested that abnormal expression of SNHG1 and miR-145 may be risk factors for restenosis. The present study revealed that the SNHG1/miR-145 axis regulates hHCtASMC proliferation and migration, indicating its potential for restenosis prevention and treatment.