The six-time MotoGP champion span off in the early stages of the race at Motorland, and was carried away on a stretcher.
Rossi was then taken the hospital for scans and Michele Zasa, Clinica Mobile Medical Director provided an update on the Yamaha rider's condition.
"Valentino suffered a concussion with a suspected loss of consciousness," he said in a brief statement.
"From a neurological point of view he has recovered very well.
"He was taken to hospital in Alcaniz to make a further check, in particular a CT scan of the skull that has ruled out any bleeding in the brain.
"As a precaution he will be observed in the coming hours, but there are no special reasons for concern."