Comments on CPT tests

What do we know about CPT symmetry? We conclude that the direcrt measurement of CPT violation leads to a result that CPT violation force is limited to about 30% of CP violating forces. The best test of CPT symmetry is to see if theoretical prediction for the phase of eta_{+-} and eta_{00} agree with experiments. We discuss uncertainties associated with this prediction, and how to improve it. A new test of CPT is also discussed.