A US team at Boston Children's Hospital say EEG traces, which record electrical brain activity using scalp electrodes, could offer a diagnostic test for this complex condition.
Experts say more work is needed to confirm the BMC Medicine study results.
There are more than 500,000 people with autism in the UK.
Autism is a spectrum disorder, which means that it is not a single condition and will affect individuals in different ways.
Commonly, people with autism have trouble with social interaction and can appear locked in their own worlds.
The latest study found 33 specific EEG patterns that appeared to be linked to autism.
Hallmark brain activity