all steroids suppress your natural test levels, it's just a question of how much. Although there is very little suppression from primo, you have to remember that you've probably been shut down for the last 14 weeks or so. Adding the primo will keep you from getting back to 100% before your next cycle. Assuming that you are going to run another 14 week cycle again, you are looking at 28 weeks plus however long you bridge of being "on". The longer you keep you natural test levels supressed, the harder it is to bring them back to normal.