What does MRO stand for? In manufacturing and purchasing, MRO stands for maintenance, repair and operations: all the supplies and labor needed to keep a plant, warehouse or building in working order, even though none of it ends up in the finished product. In aviation, the same letters mean maintenance, repair and overhaul, the business of keeping aircraft and engines fit to fly.
Think of gloves, light bulbs, lubricants, filters, spare motors and the mechanic's hours to install them. A factory cannot run without these things, yet customers never see them. That is the space MRO describes. In a drug testing context, MRO has a third meaning, a medical review officer, covered further down.
Quick facts
Stands for
Maintenance, repair and operations (industry)In aviation
Maintenance, repair and overhaulOther meanings
Medical review officer; Mars Reconnaissance OrbiterType
InitialismHow to say it
M R O, letter by letterUsed in
Manufacturing, purchasing, facilities, airlinesRelated terms
OEM, ERP, SKU, CMMS
What does MRO stand for in manufacturing?
In a plant, MRO splits into three kinds of spending:
| Letter | Word | Typical examples |
|---|---|---|
| M | Maintenance | Grease, belts, filters, scheduled checks on machines |
| R | Repair | Replacement bearings, pumps, motors, a technician's call |
| O | Operations | Safety gear, cleaning supplies, tape, hand tools, office basics |
Buyers often call these items indirect materials. Direct materials, such as the steel in a car door or the flour in bread, become part of what is sold. MRO items support the work around it. You can read more about the first word on the abbreviation for maintenance page.
Why MRO matters to a business
Individual MRO purchases are usually small, but there are a lot of them. A large site may stock thousands of different parts, each with its own SKU, bought from many suppliers. That makes MRO a common target for savings and better planning.
- Downtime: if a spare part is missing when a machine breaks, a whole line can stop.
- Too much stock: extra spares tie up money and shelf space.
- Scattered buying: many small orders from different people are hard to track.
Companies often track MRO through purchasing software or an ERP system, and many use a maintenance management tool (CMMS) to schedule work orders.
In a work email: "Please add nitrile gloves and safety glasses to the monthly MRO order." The sender wants routine supplies added to the regular purchase, not parts for a product.
MRO in aviation: maintenance, repair and overhaul
In the airline world, an MRO is often a company or a hangar, not a category of supplies. These shops inspect airframes, rebuild engines, repair landing gear and handle the heavy checks that aircraft need on a fixed schedule. Overhaul means taking a part apart, inspecting it and restoring it to a like new condition.
An airline might do some of this work itself and send the rest to an outside MRO provider. Aircraft makers, known as OEMs, often run MRO services too. When you read "the MRO market" in an aviation story, it means this repair and overhaul business.
Other meanings of MRO
| Setting | Meaning | Sample |
|---|---|---|
| Manufacturing, facilities | Maintenance, repair and operations | "MRO spending rose this quarter." |
| Aviation | Maintenance, repair and overhaul | "The engine went to an MRO for a rebuild." |
| Workplace drug testing | Medical review officer | "The MRO will call you about your result." |
| Space | Mars Reconnaissance Orbiter | A NASA spacecraft that studies Mars from orbit |
A medical review officer is a licensed physician who reviews lab results from drug tests and talks with the person tested before a result is reported to an employer. This step lets someone explain a valid prescription, for example.
Saying and writing the MRO acronym
- Purchasing teams voice it one letter at a time, "M R O," never as a single word.
- On purchase orders and budgets it appears in capitals, with no dots between letters.
- Choose "an" in front of it, because M is pronounced "em": "an MRO supplier."
- The plural for providers is MROs: "several MROs bid on the work."
A few sentences from real work settings:
- "Our MRO budget covers safety gear and spare parts."
- "The plant cut MRO costs by combining suppliers."
- "The jet is at an MRO in Texas for a heavy check."
Questions people ask
What does MRO stand for in manufacturing?
It stands for maintenance, repair and operations. The term covers supplies and services that keep a plant running but do not become part of the product.
What does MRO mean in aviation?
In aviation it means maintenance, repair and overhaul. It also names companies that service aircraft, engines and parts.
What are examples of MRO supplies?
Common examples are gloves, safety glasses, lubricants, filters, fasteners, light bulbs, hand tools, cleaning products and spare motors or bearings.
What is an MRO in a drug test?
It is a medical review officer, a physician who reviews lab results and speaks with the person tested before the result goes to the employer.
Is MRO the same as indirect spend?
MRO is a large part of indirect spend, which is money spent on things that do not go into the product. Indirect spend can also include travel, software and office services.