A study of 153 brain scans has linked a particular furrow, near the front of each hemisphere, to hallucinations in schizophrenia.
This fold tends to be shorter in those patients who hallucinate, compared with those who do not.
It is an area of the brain that appears to have a role in distinguishing real perceptions from imagined ones.
Researchers say the findings, published in Nature Communications, might eventually help with early diagnosis.
The brain wrinkle, called the paracingulate sulcus or PCS, varies considerably in shape between individuals. It is one of the final folds to develop, appearing in the brain only just before birth.
"The brain develops throughout life, but aspects such as whether the PCS is going to be a particularly prominent fold - or not -may be apparent in the brain at an early stage," said Jon Simons, a neuroscientist at the University of Cambridge, UK.
"It might be that a reduction in this brain fold gives somebody a predisposition towards developing something like hallucinations later on in life."
If further work shows that the difference can be detected before the onset of symptoms, for example, Dr Simons said it might be possible to offer extra support to people who face that elevated risk.
But he stressed that schizophrenia is a complicated phenomenon. Hallucinations are one of the main symptoms, but some patients are diagnosed on the basis of other irregular thought processes.