Objective: To examine the effect of ustekinumab on work productivity and the number of workdays missed due to psoriasis. Methods: A total of 1995 patients were enrolled in the PHOENIX I and II trials. Patients were randomized 1:1:1 to one of three groups:placebo,ustekinumab 45mg,or ustekinumab 90mg.In the ustekinumab groups, patients received treatment at weeks 0, 4, and every 12 weeks thereafter. Patients randomized to placebo at baseline crossed-over to receive either 45mg or 90mg of ustekinumab at weeks 12, 16, and every 12 weeks thereafter.Productivity was assessed using a 10cm Visual Analog Scale (VAS), and change in productivity was recorded in cm units. Productivity and number of workdays missed due to psoriasis in the last 4 weeks was evaluated at weeks 0 and 12 in both trials. Results: Mean and median baseline productivity scores and number of workdays missed due to psoriasis were similar between treatment groups at baseline. At week 12, the ustekinumab 45mg and 90mg groups had significantly greater improvements(p<0.001 for both comparisons)from baseline in productivity scores than the placebo group.The mean (median) change in productivity from baseline score at week 12 was –2.2(-1.1) for the 45mg group and –2.4(-1.4) for the 90mg group, compared with 0.0(0.0) for the placebo group. The mean(median)change from baseline to week 12 in the number of workdays missed due to psoriasis in the last 4 weeks was 0.0 (0.0) in the placebo group, -0.2 (0.0) in the 45mg group (p<0.002),and -0.3 (0.0) in the 90mg group (p<0.002).This could translate to an annualized average reduction of missed workdays due to psoriasis of 2.6 days for the 45mg group and 3.9 days for the 90 mg group. Conclusion: Ustekinumab 45mg and 90mg resulted in significantly improved productivity compared with placebo in moderate-to-severe psoriasis patients, as measured by the productivity VAS and workdays missed due to psoriasis.