Emergency services responded to reports of a shooting in Buxton on Tuesday 11 September.
Police understand two men were involved in an altercation at an address on Maroondah Highway about 9.15pm.
A 50-year-old Lilydale man sustained a gunshot wound during the incident and was airlifted to hospital in a critical condition.
Police arrested a 49-year-old Buxton man at the scene, and he remained in custody on Wednesday morning.
It is believed the parties were known to each other.
The investigation is ongoing and anyone with information should call Crime Stoppers on 1800 333 000 or submit a confidential report at www.crimestoppersvic.com.au.