This is an open-label, multicenter phase II study in patients with aggressive Non Hodgkin Lymphoma scheduled to receive moderately emetogenic polychemotherapy (according to modified Hesketh classification for antiemetic therapy).

Inclusion Criteria:

• Male or female, >18 years of age;
• Histologically or cytologically confirmed aggressive NHL (any stage in accordance with the REAL Classification);
• Patients candidates to a initial chemotherapy treatment;
• ECOG performance status of 0-1;
• Scheduled to receive a single intravenous dose of at least one of the moderately emetogenic agents (according to the modified Hesketh classification) on Day 1;
• Written informed consent;
• Female of childbearing potential must be using reliable contraceptive measures;
• Acceptable hepatic and renal functions;
• Willing and able to complete the patient diary.

Exclusion Criteria:

• Highly emetogenic chemotherapy (containing cisplatin, mechlorethamine, streptozotocin, cyclophosphamide >1500 mg/sqm; carmustine; dacarbazine; hexamethylmelamine; procarbazine), or single-agent chemotherapy with drugs having low/minimal emetogenic potential according to the Hesketh classification);
• Diagnosis of Hodgkin's Disease or Leukemia;
• Candidates to High-Dose Chemotherapy or Bone Marrow/Peripheral Blood Stem Cells Transplantation;
• Chemotherapy schedules considering the administration of emetogenic drugs in more than two consecutive days;
• Have received any investigational drugs within 30 days before study entry;
• Have received any drug with potential anti-emetic efficacy (with the exception of specific corticosteroids foreseen in the chemotherapy combination) within 24 hours of treatment initiation);
• Prior treatment with Palonosetron;
• Have a seizure disorder requiring anticonvulsant medication unless clinically stable and free of seizure activity;
• Experienced or ongoing vomiting or nausea from any organic etiology, in the screening phase;
• Clinical evidence of current or impending bowel obstruction, peritonitis, infection, uremia, severe mucositis;
• Clinically relevant electrolyte abnormalities;
• Have a known hypersensitivity to 5HT3 receptor antagonists;
• Radiotherapy within 30 days before chemotherapy administration, or scheduled to receive radiotherapy within two weeks after chemotherapy;
• Female patients who are pregnant or breast feeding;
• Inability to understand or cooperate with the study procedures.