Officers in Hounslow and the family of Muhammed Raja are growing increasingly concerned for his wellbeing.
He was last seen by his parents at around 8pm on Tuesday (March 14), at his home address in Barrack Road.
The 38-year-old, who has not gone missing before, was wearing all black clothing with a black rucksack at the time of his disappearance.
He left the address without any personal property, police said.
He has been described as 5ft 10ins tall and of medium build with short dark hair and a beard.
It is believed he has links to the Ashford area.
Officers urge anyone with information on his whereabouts to call police on 101 or Missing People on 116000.
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