Kleinpenning et al have determined previously the effect of two different NB-UVB light therapy regimens on the decrease in PASI three months after completion of a course of NB-UVB light therapy. Three months after cessation of NB-UVB light therapy the decrease in the PASI in those receiving an high-dose regimen was 5.93±4.1compared to baseline. This decrease in PASI was significantly less in the group receiving a low-dose regimen (4.14±2.96, p<0.05).