The American Society of Clinical Oncology (ASCO) updated its clinical practice guideline on antiemetics for oncology patients. The update was based on a systematic review of the medical literature, including randomized clinical trials and systematic reviews. The guideline provides updated recommendations for the use of antiemetics to prevent chemotherapy-induced nausea and vomiting (CINV) and radiation-induced nausea and vomiting (RINV). Key recommendations include the use of a three-drug combination of a neurokinin 1 (NK1) receptor antagonist, a 5-hydroxytryptamine-3 (5-HT3) receptor antagonist, and dexamethasone for patients receiving highly emetic chemotherapy. For moderate emetic risk, palonosetron is preferred as the 5-HT3 antagonist, combined with dexamethasone. For low-risk agents, dexamethasone before chemotherapy is sufficient. Patients undergoing high emetic risk radiation therapy should receive a 5-HT3 antagonist before each fraction and for 24 hours after treatment, with a 5-day course of dexamethasone during fractions 1 to 5. The guideline also addresses special populations, such as pediatric patients and those undergoing high-dose chemotherapy with stem-cell or bone marrow transplantation. It recommends a 5-HT3 antagonist combined with dexamethasone for these patients. For patients receiving combination chemotherapy, antiemetic treatment should be based on the agent with the greatest emetic risk. The guideline emphasizes the importance of continued symptom monitoring and notes that clinicians often underestimate the incidence of nausea. It also highlights the need for patient-reported outcome measures in future research. The full guideline, including detailed discussions, methodology, and references, is available at www.asco.org/guidelines/antiemetics.The American Society of Clinical Oncology (ASCO) updated its clinical practice guideline on antiemetics for oncology patients. The update was based on a systematic review of the medical literature, including randomized clinical trials and systematic reviews. The guideline provides updated recommendations for the use of antiemetics to prevent chemotherapy-induced nausea and vomiting (CINV) and radiation-induced nausea and vomiting (RINV). Key recommendations include the use of a three-drug combination of a neurokinin 1 (NK1) receptor antagonist, a 5-hydroxytryptamine-3 (5-HT3) receptor antagonist, and dexamethasone for patients receiving highly emetic chemotherapy. For moderate emetic risk, palonosetron is preferred as the 5-HT3 antagonist, combined with dexamethasone. For low-risk agents, dexamethasone before chemotherapy is sufficient. Patients undergoing high emetic risk radiation therapy should receive a 5-HT3 antagonist before each fraction and for 24 hours after treatment, with a 5-day course of dexamethasone during fractions 1 to 5. The guideline also addresses special populations, such as pediatric patients and those undergoing high-dose chemotherapy with stem-cell or bone marrow transplantation. It recommends a 5-HT3 antagonist combined with dexamethasone for these patients. For patients receiving combination chemotherapy, antiemetic treatment should be based on the agent with the greatest emetic risk. The guideline emphasizes the importance of continued symptom monitoring and notes that clinicians often underestimate the incidence of nausea. It also highlights the need for patient-reported outcome measures in future research. The full guideline, including detailed discussions, methodology, and references, is available at www.asco.org/guidelines/antiemetics.