Avoid unless you're over 40 and facing rapidly diminshing T levels (by the way I tried a bottle and did not discern any effect):
http://www.supplementwatch.com/suplib/supplement.asp?DocId=1097"DHEA supplements, at 50 – 100 mg per day, have been shown to increase muscle mass and improve overall feelings of well-being among a group of 40-70 year old subjects who took the supplements for 6 months. Another small study (9 elderly men) showed a link between 5 months of DHEA supplementation (50mg/day) and improvements in markers of immune system function (lymphocytes, natural killer cells and immunoglobulins). Several studies have shown an increased serum testosterone levels following regular DHEA supplementation (50-100mg/day)."
Also note side effects:
"Although it is difficult to show clear side effects from DHEA supplements, several publications have raised concerns regarding of altered hormone profiles, liver abnormalities, increased cancer risk (prostate in men and breast in women) and other steroid-like effects (increased facial hair, acne, mood swings). Since DHEA is converted into testosterone, there have been concerns that chronic use in men might worsen prostate hyperplasia or even promote prostate cancer."
Also note product unreliability:
"A recent publication, however, analyzed several DHEA products on the market and found a dramatic difference between the amount of DHEA stated on the supplement label and the amount actually present in the product. The range of actual DHEA present was over 150% to zero. Only 7 of the 16 products (44%) analyzed were found to have a DHEA content within the typical pharmaceutical product specifications of 90-110% of the labeled claim. Of the remaining products, no DHEA was detected in 1 product, and trace amounts were detected in 2 other products. The latter 2 were labeled as containing naturally occurring DHEA, with no specific amount indicated on the label."
