What is rtl8139?

Rtl8139.sys is a Windows driver. A driver is a small software program that allows your computer to communicate with hardware or connected devices. This means that a driver has direct access to the internals of the operating system, hardware etc. The free file information forum can help you determine if rtl8139.sys is a Windows system file or if it belongs to an application that you can trust.

Run a free scan to check for rtl8139 drivers in need of updating

Rtl8139.sys file information

The process known as Realtek RTL8139 NDIS (version 5.0 Driver) or NDIS 5.0 driver belongs to software Realtek RTL8139(A/B/C)-based PCI Fast Ethernet Adapter NT Driver or NT-Treiber für Realtek RTL8139(A/B/C)-basierten PCI-Fast Ethernetadapter by Realtek Semiconductor (

Description: The original rtl8139.sys is an important part of Windows and rarely causes problems. Rtl8139.sys is located in the C:\Windows\System32\drivers folder. Known file sizes on Windows 10/8/7/XP are 20,992 bytes (90% of all occurrences) or 23,070 bytes. 
The driver can be started or stopped from Services in the Control Panel or by other programs. The file is a Windows core system file. The program has no visible window. The service has no detailed description. It is a trustworthy file from Microsoft. rtl8139.sys appears to be a compressed file. Therefore the technical security rating is 4% dangerous, however you should also read the user reviews.

Recommended: Identify rtl8139.sys related errors

Important: Some malware disguises itself as rtl8139.sys, particularly when not located in the C:\Windows\System32\drivers folder. Therefore, you should check the rtl8139.sys process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


User Comments

i believe its harmless... just unstable as heck, there has to be a fix for this glitch. i believe there is an issue with different types of harware/software setups, because i dont see this in other laptops of the same brand and model. the only differences are in software choices. in my opinion it has to be conflicting in the system32 some how some way.i believe also if i can keep it stable long enough im going to unistall microsofts driver and install realteks latest driver. i know i know, there are some people who will say its the same driver...
file needed 4 ethernet driver

Summary: Average user rating of rtl8139.sys: based on 5 votes with 3 user comments. 3 users think rtl8139.sys is essential for Windows or an installed application. One user thinks it's probably harmless. One user thinks it's neither essential nor dangerous. One user is not sure about it.

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Best practices for resolving rtl8139 issues

A clean and tidy computer is the key requirement for avoiding problems with rtl8139. This means running a scan for malware, cleaning your hard drive using cleanmgr and sfc /scannow, uninstalling programs that you no longer need, checking for Autostart programs (using msconfig) and enabling Windows' Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the rtl8139.sys process on your computer, the following programs have proven to be helpful: Security Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. Malwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

rtl8139.sys [all]