Sarah,Im in the UK and have just managed to persuade my GP to get me a test for SIBO. Took a lot of persuading though. The NHS wont pay for many things these days. If you meet a lot of resistence you could ask your GP to refer you to a private hospital to have the test. That way you either get the test done (and have to pay for it) or they panic a bit that they might suffer some repercussions for not helping you on the NHS if the tests prove to be positive, and end up arranging the test on the NHS (which is what happened to me!) Have you been seen by a gastro and been officially diagnosed as IBS or have you self-diagnosed? If you are on the thin side despite eating a lot, its worth pursuing this SIBO idea. From what I can gather, the bacteria (which have invaded the small intestine) steal a lot of the nutrients out of the food before it gets to the colon where you get the chance to get at it! If you havent been refered to a gastro yet, I would ask your GP to do this, and then pursue the SIBO testing idea with them. Gastro probably wont mention SIBO himself - they are a chronically busy/underfunded discipline and will just want you in and out as quickly as poss with a diagnosis of IBS. The symptoms for IBS and SIBO are very simillar. Call me cynical, but the NHS automatically labels people as having IBS because there is no known cause/cure, so they dont have to do anything, just diagnose IBS and you are off their patient list. Whereas with SIBO there is a definate problem - bugs that should be in colon have got into small intestine and there are things they have to do to treat it (antibiotics, retesting etc) and there can be fairly serious medical repercussions if they dont treat it/ treat it properly (which involves come-back on them.) From their point of view its a waste of a lot of their departments resourses to treat something that isnt on their / their managers / politicians priority condition list (the big 5, or whatever they are calling it these days.....)Sorry - you just wanted to know where to get the test! .......Do a google search for "SIBO hydrogen breath test NAME OF YOUR NEAREST BIG CITY HOSPITAL" and hopefully a list will come up with all the tests you hospital lab does. Thats how I found out, so when my GP tried to dismiss my silly SIBO idea with, "I am not aware of any such breath tests" I was able to hand her a piece of paper with the extention number and contact name of the biochemist in the local lab who does the test.