This is a long article, but a really good one, I think. Some of the tests mentioned are:SPECT, MRI, and PET scans of the brain, Neuropsychological testing, EEG and QEEG brain maps, Romberg testing, tests of the Immune System, RNase L, SED rates, Glucose and Insulin testing, 24 hour Holter Monitor, Tilt Table Examination, Exercising and Chemical Stress Testing, and a few others.Each test is briefly explained, along with the reasons it can be useful in diagnosing ME. It's a long article, so you might want to scroll down to the specific test that interests you. But it's a really good article, if you decide the read the whole thing!http://www.ahummingbirdsguide.com/testingforme.htm