Just read this on a PCOS forum that someone else said.... "These are my thoughts on them. It depends on the person and the hormone profile. In the medical profession, there are 2 distinct categories/causes of PCOS. Those with insulin resistance and those with high levels of leutenising hormone (LH - high for many reasons, but features in thinner women). OPK test for a huge surge of LH which occurs immediatly before (and triggers) ovulation. Presumably if you had really high LH levels with PCOS, you would test + on an OPK even if you werent ovulating. " Also mentioned on the forum is how PCOS sufferers try to ovulate a few times in one cycle so an OPK would pick up the rise in LH but then you dont actually ovulate.