A woman has been charged after allegedly injuring her boyfriend's genitals so badly he needed surgery.

Police said the man and woman, both aged 50, had been drinking for several hours when they got into a disagreement at their home in West Busselton at 8:20pm on Tuesday.

The altercation escalated into a physical fight and the woman caused significant injury to the man's genitals, police allege.

The ABC has been told the man's scrotum was torn open and required surgery.

The man was taken by ambulance to Busselton Health Campus before being transferred to Bunbury Regional Hospital.

A 50-year-old woman has been charged with aggravated unlawful wounding.

She briefly faced the Bunbury Magistrates Court today and was refused bail.

She is due to face court again tomorrow.