Background: Vitamin D deficiency may be an easily detected peripheral neuropathy (PN) risk factor that could be resolved prior to treatment to prevent PN, avoid treatment disruptions, and improve treatment outcomes. This study examined the relations between Vitamin D level before therapy and PN severity during weekly paclitaxel treatment. Subjects and methods: This prospective study analyzed data from 38 patients enrolled in an observational cohort study to receive sequential weekly adjuvant paclitaxel for breast cancer. After (AC) Anthracyclines (Doxorubicin), cyclophosphamide (Endoxan) based chemotherapy, patients had HER2 enriched, luminal b HER2 positive received both paclitaxel and trastuzumab (Herceptin) monoclonal antibody against HER2. Life Satisfaction Chemotherapy-Induced Peripheral Neuropathy (CIPN20) Questionnaire was assessed at the beginning of treatment and once weekly until the end of the treatment, we added nerve conduction study (NCS) nerve conduction velocity (NCV) for better assessment. CIPN was assessed by Adapted NCI Common Terminology Criteria for Adverse Events (CTCAE) version 6.0 Results:There was a significant relationship type and grade of peripheral neuropathy. With an area under the curve of 0.864, specificity of 83.3%, sensitivity of 80%, positive predictive value of 84.2%, negative predictive value of 78.9%, and overall accuracy of 81.6%, a vitamin D cutoff of 30.75 ng/ml was effective in predicting the occurrence of peripheral neuropathy. Conclusion: Patients with breast cancer receiving weekly paclitaxel also reported more PN if they had a vitamin D deficiency at baseline. This work adds to the growing body of data that vitamin D is a useful biomarker for predicting paclitaxel-induced peripheral neuropathy.