BACKGROUND The duration of untreated illness (DUI) is a measure to express the latency to first psychopharmacological treatment: it differs among psychiatric disorders, being influenced by several illness-intrinsic and environmental factors. The present study aimed to assess differences in DUI and related variables in patients with schizophrenia (SKZ) versus other schizophrenic spectrum disorders (SSDs) across different epochs. METHODS 101 SKZ or SSD patients were assessed with respect to DUI and related variables through clinical interview and questionnaire. RESULTS Patients with SKZ showed earlier ages of onset, first diagnosis and first antipsychotic treatment compared with patients with other SSDs (F = 11.02, p < 0.001; F = 12.68, p < 0.001; F = 13.74, p < 0.001, respectively) who showed an earlier access to benzodiazepines than SKZ patients (F = 6.547; p < 0.05). Dividing the total sample by the epoch of onset (before 1978; between 1978-2000; after 2000) showed a significantly later age of onset in patients with onset within the two most recent epochs (F = 7.46; p < 0.001) and a reduced DUI across epochs (from 144 to 41 to 20 months, on average; F = 11.78, p < 0.001). CONCLUSIONS Schizophrenic patients showed earlier onset and longer DUI compared with patients with other SSDs. Data on the total sample showed a later age of onset and a reduced DUI across epochs.