If you have a relationship with a co-worker that is so contentious you're considering leaving your job because of that person, first step back to examine the situation and see if you can resolve the conflict. If your company offers dispute mediation or conflict resolution assistance, start there. Walking away from a job because of one person throws away the time and effort you've put into your career.

Talk to Your Supervisor

Have a frank and honest conversation about the problems you're having with your colleague. Be as direct and specific as possible. For example, if the colleague harasses you, takes credit for your work or attempts to coerce you into handing over your responsibilities, describe these actions. Explain the ways you’ve tried to fix the problem on your own and let your boss know what kind of resolution you want. If the staffer is violating company policy with her actions, your manager might take steps to intervene or put the employee on notice that continued bad behavior will result in suspension or termination.

Talk to Your Colleague

Make an introspective assessment of what role, if any, you play in creating a contentious relationship with your co-worker. Ask yourself if you’re contributing to the problem and if changes or alterations to your behavior or ways of thinking might calm the conflict. If you haven't had an honest, private conversation with your colleague about your issues, do so in an effort to avoid sacrificing your job. Sometimes, annoying or passive-aggressive people aren't aware of how their behavior impacts others. Bring it to her attention and try to discover ways you can work together in a professional capacity.

Explore Options

You may have options other than quitting your job. Talk to your boss about a transfer to a different department, a move to another desk or a group reassignment to create distance between you and your colleague. You might be able to change your shift, telecommute or work from home to limit the amount of time you spend with the offending co-worker.

Give Your Notice

If you explored all options and can see no potential way to continue working with your problem colleague, make an appointment to talk to your boss privately and announce your resignation. Be professional and give at least two weeks’ notice. Offer to complete outstanding work and make the transition into your role easier for the next staffer. Put your resignation in writing and let your boss know you made your decision because of unresolved differences with your co-worker.

Find a New Job

Be prepared to answer questions from prospective new employers about why you ended your previous role. Admitting you had an unsolvable issue with a co-worker has the potential to paint you as a difficult employee who is hard to get along with. Instead, tell prospective employers you're looking for new challenges and opportunities not available with your last company.