Participants take their usual medications for fibromyalgia in addition to either neurotropin or a placebo (look-alike medicine with no active ingredient). At 6 weeks and 12 weeks into the study, they return to the NIH Clinical Center for evaluation of their sensitivity to pain and level of physical capability. After 12 weeks, study subjects "cross-over" their medication; that is, patients who took neurotropin for the first 12 weeks of the study take placebo for the next 12 weeks, and vice-versa. Again, after 6 and 12 weeks, patients return for evaluation.