Purpose: To assess the invariance of a culturally competent multi-lingual unmet needs survey.Methods: A cross-sectional study was conducted among immigrants of Arabic, Chinese and Greekspeaking backgrounds, and Anglo-Australian-born controls, recruited through Cancer Registries (n = 591) and oncology clinics (n = 900). The survey included four subscales, with newly developed items addressing unmet need in culturally competent health information and patient support (CCHIPS), and items adapted from existing questionnaires addressing physical and daily living (PDL), sexuality (SEX) and survivorship (SURV) unmet need. The measure was translated into Arabic, Chinese and Greek. Rasch analysis was carried out on the four domains.Results: While many items were mistargeted to less prevalent areas of unmet need, causing substantial floor effects in person estimates, reliability indices were all acceptable. The CCHIPS domain showed differential item functioning (DIF) for cultural background and language and the PDL domain showed DIF for treatment phase and gender. The results for SEX and SURV domains were limited by floor effects and missing responses. All domains showed adequate fit to the model after DIF was resolved and a small number of items were deleted.Conclusions: The study highlights the intricacies in designing a culturally competent survey that can be applied to culturally and linguistically diverse groups across different treatment contexts. Overall, the results demonstrate that this survey is somewhat invariant with respect to these factors. Future refinements are suggested to enhance the survey's cultural competence and general validity.Identification of the unmet supportive care needs of cancer patients and survivors informs appropriate resource allocation and optimisation of service provision relative to actual needs [1][2][3][4].To date, such assessment has focused on non-immigrant cancer patients. Immigrant groups diagnosed with cancer are worse off than comparable non-immigrant groups in terms of survival [5], psychological morbidity and quality of life [6]. These disparities may arise from a lack of familiarity with the healthcare system, lack of culturally appropriate information, communication difficulties for culturally and linguistically diverse (CALD) patients, and cultural attitudes and beliefs toward cancer [7][8][9]. Thus there is an imperative to develop and validate a questionnaire to assess unmet needs in immigrant cancer patients and survivors [2,10,11].Existing unmet needs questionnaires address themes that may be common to immigrant and nonimmigrant cancer survivors, including needs related to the health system and information, physical and daily living, patient care and support, sexuality, and survivorship [1,4,7]. However, immigrants may have unique needs as a result of the issues outlined above [7]. Furthermore, the interpretation of items and scores must remain invariant across diverse languages and cultural groups to enable valid comparisons.Rasch analysis provides a robust me...