A literature search of all randomized controlled trials (RCTs) on psoriasis conducted from 2001-2006 has been published. It is an update and a comparison with an earlier survey published in 2003 that reviewed trials from 1997-2000. A total of 140 and 249 RCTs were found in 1997-2000 and 2001-2006, respectively. The proportion of placebo-controlled studies had increased from 44.6% to 69.3% and the median study duration from 7 to 12 weeks. The Psoriasis Area and Severity Index (PASI) was used in 57.7% of the recent trials but in only 30.6% of the earlier studies. Quality of life studies were conducted in 7.7% of recent studies versus 0.4% of the earlier ...