Drugs & infusions
J9355 — Trastuzumab (Herceptin) injection, 10 mg
Targeted breast cancer therapy. Billed by 10 mg unit — a single dose can be 100+ units.
- Typical setting: Hospital infusion or oncology clinic
- National avg charge (illustrative): Insurance allowed $50-$200 per 10 mg unit; total per dose $4,000-$20,000+.
- Most-disputed reason: Wastage units billed without documentation.
What it means
What J9355 actually means
HCPCS J9355 is the per-10-mg billing code for trastuzumab (brand: Herceptin), a targeted therapy for HER2-positive breast cancer. A typical dose is hundreds of milligrams.
Common errors with this code
What goes wrong on real bills.
Most bills that look correct still contain at least one of these issues. Up to 49% of medical bills contain errors (CFPB).
- Wastage units (JW modifier) billed without proper documentation.
- Unit count inflated beyond actual administered dose.
- Coded as biosimilar or originator inappropriately for payer rules.
If you see J9355 on your bill
Three steps before paying.
1. Get the itemized bill. If your statement only shows a summary, request the CPT-level itemized bill before paying. Generate the request language →
2. Cross-check against the EOB. Compare what your insurer's Explanation of Benefits says you owe versus what the hospital is asking. They disagree more often than people think. Read the bill-vs-EOB guide →
3. Run a free Bill Scan. Upload the bill (and EOB if you have it) and BillBusted will flag the most likely issues with this specific code in your specific state. Run free scan →
Related codes
Other codes in this category.
People who land on J9355 often also see these adjacent codes on the same bill.
Related BillBusted guides
Plain-English reads if you see J9355 on a bill.
J9355 FAQ
Plain-English answers.
Don't pay J9355 blindly.
The free scan tells you in under 60 seconds whether this charge looks reasonable for your situation.