Anyone preparing for a certification exam is interested in knowing about the general pass percentage out of the candidates that appear in that exam. Similarly, those preparing for CISA exam are interested in CISA pass rate.
To be precise ISACA does not release any data about CISA pass percentage. Therefore, the only possible way to get any information about is visiting different certification forums where CISA candidates post their results.
CISA Pass Rate
Just to give you an idea of the pass percentage, have a look at this Yahoo Answers thread where people shared their results for CISA Exam August 2008 as they were receiving the results emails. (I myself also passed CISA exam in that attempt and you can also find my 7 years old comment in this Yahoo answers thread :).
You can see that a lot people have declared themselves as Passed and some with scores as high as 713. I also remember reading an official presentation from an ISACA Chapter (I think it was Indonesia) which had stated that the general pass rate for that country has been around 50 percent. Similarly most people agree that generally the CISA pass rate is between 45 to 60 percent. And my understanding is that it varies from country to country too.
But the pass rate is only an indication of your chances of passing the exam because CISA uses a scaled scoring system. And you need to score at least 450 on the scaled score to pass the CISA exam.
I also know many of my peers and friends who have sat for CISA exam in the past and I am also inclined to believe that the CISA pass rate hovers around 50 percent. But your chances of passing CISA exam are higher than 50 percent if you are coming from an Information Technology background. With the recent increase in the weightage given to IS audit process, I consider that chances of passing the exam have increased for candidates with auditing background too.
But whatever the general CISA pass rate, the ultimate determining factor is how well you prepare for the exam and how you perform on the exam day. Good luck!