Children aged 4-15 years scheduled to receive Moderate or low emetic chemotherapy were randomly assigned to arm-A (Ondansetron mouth soluble film) or arm-B (Ondansetron tablet). Children recruited to arm-A received ondansetron mouth soluble film plus dexamethasone. Children recruited to arm-B received Ondansetron tablet plus dexamethasone. Ondansetron and dexamethasone were given continuously until 48hours after completion of chemotherapy. The primary end point of the study was to determine the proportion of patients who achieved a CR, defined as no vomiting, no retching, and no use of rescue medication, the proportion of patients who achieved a CR during the acute phase (0-24 hours) after administration of the last dose of chemotherapy. Secondary end points were the proportion of patients who achieved a CR during the 24-120 hours (delayed phase) and overall after administration of the last dose of chemotherapy

Inclusion Criteria:

• Patients aged 4 to 15 years who have been diagnosed with malignant tumor through pathological examination and need to receive chemotherapy, gender is not limited;
• Receive moderate and low grade emetic chemotherapy;
• Patients with a score greater than 60 or higher have a life expectancy greater than 3 months;
• The patients were enrolled voluntarily, and the family members signed the informed consent, and the family members had good compliance and accurately recorded the vomiting diary.

Exclusion Criteria:

• Children allergic to 5HT3 antagonists;
• Active infection;
• Abnormal bone marrow function (absolute neutrophil count <1000/mm3 platelet count <100000/mm3);
• Abnormal renal function in serum creatinine beyond the upper age limit of normal (ULN);
• Abnormal liver function of serum aspartate aminotransferase and alanine aminotransferase, age and serum bilirubin are 1.5 times that of ULN;
• vomiting 24 hours before chemotherapy begins;
• Start systemic corticosteroid therapy within 72 hours prior to study drug use, or plan to receive corticosteroids as part of a chemotherapy regimen;
• Patients with benzodiazepines or opioids