Purpose We examined the efficacy and safety of thalidomide (THD) for the prevention of delayed nausea and vomiting in patients who received highly emetogenic chemotherapy (HEC). Patients and Methods In a randomized, double-blind, active-controlled, phase III trial, chemotherapy-naive patients with cancer who were scheduled to receive HEC that contained cisplatin or cyclophosphamide-doxorubicin/epirubincin ≥ 50 mg/m2 regimens were randomly assigned to a THD group (100 mg twice daily on days 1 to 5) or placebo group, both with palonosetron (0.25 mg on day 1) and dexamethasone (12 mg on day 1; 8 mg on days 2 to 4). Primary end point was complete response to vomiting-no emesis or use of rescue medication-in the delayed phase (25 to 120 h). Nausea and anorexia on days 1 to 5 were evaluated by the 4-point Likert scale (0, no symptoms; 3, severe). Quality of life was assessed by the European Organization for Research and Treatment of Cancer QLQ-C30 version 3 questionnaire on days -1 and 6. Results Of 656 patients, 638 were evaluable: 317 in the THD group and 321 in the control group. Compared with placebo, delayed and overall (0 to 120 h) complete response rates to vomiting were significantly higher with THD: 76.9% versus 61.7% ( P < .001) and 66.1% versus 53.3% ( P = .001), respectively. Rates of no nausea were also higher in the THD group (delayed: 47.3% v 33.3%; P < .001; overall: 41% v 29.6%; P = .003), and mean scores of anorexia were lower overall (0.44 ± 0.717 v 0.64 ± 0.844; P = .003). Adverse effects were mild to moderate. The THD group had increased sedation, dizziness, constipation, and dry mouth, but experienced better quality of life after chemotherapy. Conclusion Thalidomide combined with palonosetron and dexamethasone significantly improved HEC-induced delayed nausea and vomiting prevention in chemotherapy-naive patients.