Suppose I have variables $x1 = 'XX a b XX c d XX'; $x2 = 'XX a b XX c d XX e f XX'; I want a regular expression that will find each instance of letters between XX. I'm looking for a general solution, because I don't know how many XX's there are. I tried using /XX(.*?)XX/g but this only matches "a b" for x1 and "a b", "e f" for x2 because once the first match is found, the engine has already read the second "XX". Thanks for any help.