A co-worker might be rude because he's trying to assert his dominance, impact your morale or because he lacks professional and social skills. Regardless of what's behind the rudeness, you don't have to tolerate this behavior. Be proactive in how you handle rude colleagues and employ the help of your supervisor if necessary to curb this type of unprofessionalism.
Address the Rudeness
Call out a rude colleague and point out the bad behavior for what it is. For example, if a co-worker interrupts you during a meeting, says something unprofessional or unkind about one of your ideas or suggestions, say, “That was very rude.” See what kind of response you get before you decide how to proceed. The co-worker may be embarrassed and recognize his gaff, or he may elevate hostility and defend his behavior. If the colleague heaps bad behavior on top of rudeness, that's an indication of potential workplace hostility and should be carefully monitored, if not immediately reported to your supervisor.
Denounce the Behavior
Stand up for yourself and refuse to tolerate rudeness from the first instance of bad behavior. Rude people tend to be most unprofessional with those they know they can walk over. Let it be known from the first sign of bad behavior that you won’t tolerate being mistreated at work. Speak up immediately. “I don't appreciate that tone of voice,” or, “I refuse to talk to you when you're being rude,” or, “That type of language is unacceptable to me.”
Confront in Private
Sometimes colleagues act poorly as a way to bolster themselves in front of others or to cover for their own inadequacies in group situations. Talk to this person in private and address your concerns. Ask questions to give you an idea of what's behind the behavior while simultaneously taking an assertive approach to let it be known you're not a pushover. For example, “You interrupt me every time I begin my report in a meeting, and I find that incredibly rude. Do you have a problem with me, or is there something we need to talk about so we can work together effectively?”
Ask for Mediation
After you've tried to handle the situation on your own, if you don't see marked improvement, it may be time to bring in a human resources representative or supervisor to help mediate the conflict. Keep track of specific examples of rude behavior that you can bring into a mediation session. A good mediator will ask each of you questions about workplace behaviors and your perception of one another and get to the bottom of what's behind the rude behavior. Your colleague will likely be sanctioned or reprimanded for his actions and put on notice that unprofessional behavior will not be tolerated in the future.