Purpose: This study aimed at expanding the knowledge of nausea in patients with advanced cancer by elucidating (a) the prevalences of patients having nausea, experiencing nausea as a problem, and having a need for help with their nausea, respectively, (b) determining variables associated with nausea, and (c) investigating the relation between nausea and the need for help regarding nausea. Methods: In 2004–2006, the EORTC QLQ-C30 and the Three-Levels-of-Needs Questionnaire (3LNQ) were mailed to 2364 patients with advanced cancer who had been in contact with one of the 54 hospital departments within the past year. Further information was collected from medical records. Results: Patient-response rate was 61%. Twenty-two percent reported having had some degree of nausea within the past week, with a mean nausea score of 10.4 and a two-item combined nausea and vomiting score of 7.5 (0–100, 100 = “very much”). Factors associated with nausea on the multivariate level were contact type (inpatient/outpatient) and treatment status (receiving ongoing oncologic treatment yes/no). “Nausea intensity” and “nausea problem burden” showed acceptable abilities to distinguish between patients having or not having an unmet need for help regarding nausea with areas under the curve (AUCs) of 0.81 and 0.82, respectively. Conclusions: Around one in four patients with advanced cancer reported nausea within the past week, highest in patients who were inpatients or undergoing active oncologic treatment. Almost all patients reporting nausea on the EORTC QLQ-C30 experienced this to be a problem, and the 3LNQ can therefore be restricted to cases where additional details are needed.