Officers were called to Tynedale Road at 1pm yesterday where a man was taken to hospital in a serious condition.
A 27-year-old man was arrested at the scene on suspicion of attempted murder.
A spokeswoman for West Midlands Police said: "We were called to reports of a stabbing on Tynedale Road, Birmingham at 1pm on Saturday.
"A man, believed to be in his 70s, was taken to hospital in a serious condition.
"A 27-year-old man was arrested at the scene on suspicion of attempted murder. He remains in custody.
"Investigations are in the early stages to establish the circumstances that led to this incident.
"Anyone with information can contact us via live chat on our website or by calling 101. Please quote log number 1490 of 16/01."