Primary progressive aphasia (PPA) syndrome is frequently misdiagnosed--particularly in favour of Alzheimer's disease (AD). Misdiagnosis is related to the heterogeneity of language disorders at onset, variability in the rate of clinical progression and the low prevalence of PPA syndrome, compared with AD. The aim of this study was to determine whether a patient's first Mini Mental Status Examination (MMSE) might provide insight into differentiating between PPA and AD. We compared item scores for the first, complete MMSE in consecutive patients with PPA versus matched patients with AD. Word recall and constructional praxis were significantly better in patients subsequently diagnosed as suffering from PPA. Patients with AD performed significantly better in terms of word registration, object naming, repetition and verbal direction. Our findings indicate that the various MMSE item scores may be helpful in differentiating PPA and AD in the first few years of the disease.