Depression is frequently associated with cerebrovascular disease. Early detection and intervention in depression may enhance rehabilitation potential. Difficulties encountered by clinicians in identifying depression in patients with cerebrovascular disease are numerous. This two part review focuses on issues related to the diagnosis of depression with emphasis on recognition of depressive symptoms and their relevance to the diagnosis of depressive syndromes in the presence of vascular lesions and associated neurological deficits. Furthermore, the value of diagnostic instruments and biological markers in identifying depression following stroke has been critically evaluated. In this first part of this two part paper, phenomenological and nosological aspects are considered with an emphasis on symptom profile, significance of vegetative symptoms and other related emotional responses such as catastrophic reaction, emotionalism and apathy in the diagnosis of depression following stroke. The applicability of diagnostic subcategories to define depressive syndromes associated with cerebrovascular disease and its clinical relevance is also discussed. The authors stress that knowledge on phenomenology of depression and other emotional responses related to cerebrovascular disease will facilitate better understanding of its clinical presentation and may improve diagnostic acumen.