Purpose: To identify effective and safe interventions to prevent acute phase chemotherapy-induced nausea and vomiting (CINV) in adult and pediatric patients. Methods: We conducted a systematic review of randomized trials evaluating interventions to prevent acute CINV. Outcomes assessed were complete chemotherapy-induced vomiting (CIV) control, complete chemotherapy-induced nausea (CIN) control, complete CINV control, and discontinuation of antiemetics due to adverse effects. Results: The search identified 65,172 citations; 744 were evaluated at full-text, and 295 (25 pediatric) met eligibility criteria. In patients receiving highly emetogenic chemotherapy (HEC), complete CIV (risk ratio (RR) 1.23, 95% confidence interval (CI) 1.05–1.44) and CIN (RR 1.34, 95% CI 1.10–1.62) control improved when olanzapine was added. The addition of a neurokinin-1 receptor antagonist (NK1RA) to a corticosteroid plus a serotonin-3 receptor antagonist (5HT3RA) also improved complete CIV (RR 1.11, 95% CI 1.08–1.14) and CIN (RR 1.05, 95% CI 1.01–1.08) control. Compared to granisetron/ondansetron, palonosetron provided improved complete CIV control when the 5HT3RA was given alone or when combined with dexamethasone. In patients receiving moderately emetogenic chemotherapy (MEC), dexamethasone plus a 5HT3RA improved complete CIV control compared to a 5HT3RA alone (RR 1.29, 95% CI 1.21–1.39). Only a single meta-analysis evaluating the safety outcome was possible. Conclusions: For patients receiving HEC, various antiemetic regimens improved CIV and CIN control. For patients receiving MEC, administration of a 5HT3RA plus dexamethasone improved CIV control. Analysis of antiemetic safety was constrained by lack of data.