quit smoking for almost six months, smoked a joint one weekend, then a couple bowls the next weekend, didn't smoke for two weeks, smoked a half a joint on a sunday afternoon and took a piss test 29 days later (gas chromatograph/mass spectroscopy) and FAILED! beware folks......you can pass an EMIT test (home drug test) with ease but if you are to take the GC/MS test be forewarned! that is a sensitive test so always remember to DILUTE! i got fired from a good job two years ago for failing a piss test (my dumbass!), i had always done the substitution thing but figured 29 days was good enough....wrong! BTW, i'm 5'7" and 195 lbs. fairly high metabolism at the time as i was a mechanic at a steelmill (lots of climbing, strenuous work and HEAT!!). so hot there you'd sweat bullets in january