The short-form Cancer Needs Questionnaire (CNQ) is a self-administered cancer-specific questionnaire designed to assess patients' needs across several domains. The purpose of this study is to further evaluate its internal consistency and construct validity, in a group of ambulatory patients with cancer. Four hundred and fifty patients with a variety of cancer types participated. Factor analysis reproduced five domains: psychological; health information; physical and daily living; patient care and support; and interpersonal communication needs. Cronbach's alpha coefficients ranged from 0.94 to 0.77, indicating substantial consistency across items grouped in the five domains. A priori predictions regarding convergent and contrasting groups construct validity were explored using bivariate relationships between domains of the short-form CNQ, the EORTC QLQC-30 and Beck Depression Inventory (short-form), with support provided for most of the predictions. The current study provides supportive evidence that the short-form CNQ is a reliable and valid instrument for assessing the needs of patients with cancer in an ambulatory care setting.