Ustekinumab is a human IgG1κ monoclonal antibody that binds with high affinity and specificity to the p40 protein subunit shared by both the interleukin-12 and interleukin-23 cytokines. This study reviews clinical response and adverse events in 119 psoriasis patients who have received ustekinumab for a minimum of 1 year. The medical records of 119 psoriasis patients treated with ustekinumab at our referral clinic in Dallas between 2009 and 2013 were reviewed for response rates, side effects, and concomitant therapies. Of 119 patients, 117 (98%) had plaque type psoriasis, with 40 (34%) patients having psoriasis affecting either their palms and/or soles. Forty-four (37%) patients had psoriatic arthritis. The median follow-up period was 31 months. Fifty-six (47%) of the 119 patients obtained near complete clearance (response of more than 90% of initial body surface area involvement) upon the final follow-up visit or at the time of ustekinumab treatment discontinuation. Concomitant systemic treatments, primarily methotrexate, were given to 59 (50%) patients. Twenty-three (19%) patients discontinued treatment, primarily for sub-optimal response or loss of response. Fifty (42%) patients required either an increase in the dose of ustekinumab to 90 mg and/or administration more frequently than every 12 weeks to achieve and maintain psoriasis clearance.