Acute porphyrias are rare, but often misdiagnosed and may take a dramatic clinical course. The combination of various internal, psychiatric and neurological symptoms can mimic different other diseases. We report a 40-year-old female patient who was admitted with a subacute tetraparesis. During the last 2 months the patient was treated several times because of abdominal pain and just before admission to our clinic in a psychiatric hospital because of acute mental changes and hallucinations. The typical combination of abdominal pain, motor neuropathy and psychiatric symptoms confirmed by increased amounts of porphyrins and their precursors, led us to promptly diagnose acute intermittent porphyria. Better knowledge about the pathogenesis has clearly improved the prognosis of acute porphyria. In remission, measurement of enzyme activities or mutation screening can be the only diagnostic verification. A mutation screening for family members should be conducted to identify symptom-free carriers, especially in cases of a positive family history.