The objective was to collect normative data for a simple and a complex version of a picture description task devised to assess spontaneous speech and writing skills in patients with Alzheimer’s disease (AD), and to test whether some aspects of spontaneous language can discriminate between normal and pathological cognitive decline. Two hundred and forty English-speaking healthy volunteers were recruited to participate in this normative study. Thirty patients with a clinical diagnosis of minimal to moderate probable AD were also recruited. Age and education influenced some aspects of spontaneous oral and written language whereas sex had no influence on any of the variables assessed. A high proportion (>70%) of AD patients performed below cut-off on those scales that measured semantic processing skills. Deficits were detected even amongst those in the very early stage of the disease when the complex version of the task was used. Prospective assessment of spontaneous language skills with a picture description task is useful to detect those subtle spontaneous language impairments caused by AD even at an early stage of the disease.