Police in District 1 fined the 27-year-old man VND1.5 million (US$61.74) on Monday after catching him spraying black paint on a wall of Saigon General Hospital.
He told the police that he was painting the word "skuli" in graffiti style based on the nickname his family calls him at home.
His purpose is to leave a trademark on places he visits.
The man, who resides in the southern Kien Giang Province, was also made to repaint the hospital wall that same day.
Saigon General Hospital at 125 Le Lai Street is one of the oldest hospitals in Ho Chi Minh City which was developed from a clinic built in 1914.