A 51-year-old man is in custody after an incident in Byford overnight.
Police and ambulance officers were called to Binshaw Avenue after an altercation broke out between a number of people from two neighbouring properties.
A 35-year-old man received a serious cut to his shoulder and a further wound to his thumb, believed to be from a weapon.
He was taken by ambulance to Royal Perth Hospital.
Two cars outside the homes were also damaged in the incident.
Inquiries are continuing.