I"m doing the Denufosol study right now, originally only for 6 months and now I've committed to a whole year. I get compensated for "travel expenses" plus each office visit, for a total of around 700 dollars. I've done a good handful of studies over the years and have always gotten compensation, especially when they involve office visits. In addition to the money, I often get new equipment (nebulizers and compressors) that I get to keep. I've found that if you ask, they will give!