The time limits for filing your workers' compensation claim in Oregon are strict. For and "injury" claim, you must file a written claim within 90 days of the date of your injury. There are a lot of arguments about what constitutes a "written" claim. Typically, your employer should provide you with an 801 claim form.
In some cases, my clients work for hostile employers. I recommend going to the Oregon Workers' Compensation Website, and searching for the insurance coverage information using the Employer Coverage Database. You can then contact the insurance company directly, and file your claim.
If you are filing an "occupational disease" claim, you have one year from the date you knew or should have known about the occupational disease. A common example of an occupational disease is occupational hearing loss. If you go to a physician for an audiogram, and here she tells you that your hearing loss is due to exposure to noise at work, you are on notice of an occupational disease, and the one-year clock to file your claim begins ticking.