The boys, who are 16 and 17 years old, denied the charges Friday in the Los Angeles County Juvenile Court in Pasadena, said Shiara Dávila-Morales, county district attorney spokeswoman.
The boys remained in custody on Friday, she added.
They were arrested this week after Glendale police said they allegedly stabbed the man about 11:18 p.m. in the intersection of Doran Street and Columbus Avenue.
He was taken to Los Angeles County-USC Medical Center. Police said he will likely remain in the hospital’s critical care unit for two weeks.
Authorities have released few details about the stabbing due to their ongoing investigation.
But police said witnesses provided descriptions of the alleged attackers, from which detectives were able to identify two possible suspects.
Detectives detained the 16-year-old boy just after 9 a.m. Wednesday at Hoover High School. The second boy was arrested at his home in Glendale.
Detectives were still trying to determine whether the boys have any gang affiliation.
The teens are scheduled to appear Sept. 20 in juvenile court for a hearing to determine whether they should be tried as adults.