Anxiety symptoms and anxiety disorders are highly prevalent among older adults, and are associated with considerable distress, functional impairment, and burden. Also, there is growing need for brief instruments to measure anxiety symptoms in primary care and geriatric medical settings. Therefore, the current study focuses on the development and psychometric evaluation of a short-form of the Geriatric Anxiety Scale (GAS-G), a well-established anxiety instrument for use with older adults. Study 1 draws on the original data from the GAS-G validation study (N = 242) to develop the short-form (GAS-G-SF) and determines whether the results replicate with the short-form. Study 2 extends the validation of the GAS-G-SF to a clinical sample (N = 156; 62 patients with heart disease, 94 patients with Parkinson's disease). Overall, the GAS-G-SF showed promising psychometric properties in terms of internal consistency and validity. Also, the GAS-G-SF showed good discriminatory power based on receiver operating characteristic curve analysis in both studies. These results support the utility of the GAS-G-SF as a brief assessment measure for anxiety.