OBJECTIVES: To evaluate the relationship between weight and dose for patients initiating ustekinumab, a biologic treatment for moderate to severe plaque psoriasis. The recommended dosing for ustekinumab is 45mg for patients ≤100kg or 90mg for patients >100kg delivered as a subcutaneous injection at weeks 0, 4, and every 12 weeks thereafter.  METHODS: Patients receiving ustekinumab through Diplomat Specialty Pharmacy (DSP) were surveyed to provide their weight. Inclusion criteria were:  ≥18 years, diagnosis of psoriasis and ≥2 doses of ustekinumab. DSP provided ustekinumab shipment quantities and dates.  Shipped quantities and schedule were jointly used to estimate ambiguous doses (e.g., if two 45mg doses were in the index shipment, the index dose was estimated to be 90mg if the second shipment was within 3-5 weeks; the index dose was estimated to be 45mg if the next shipment was 12-18 weeks).  RESULTS: Of 257 patients surveyed, 65% (166) weighed ≤100kg and 35% (91) weighed >100kg.  Of those ≤100kg, 83% (138) received a single 45mg index dose; 11% (19) received a single 90mg dose.  Of those >100kg, 16% (15) received a single 45mg and 59% (54) received a single 90mg dose.  Thirty-one patients received two or more 45mg doses in the index fill (9 ≤100kg and 22 >100kg).  Based on timing of the second fill for those patients, the index dose was estimated to be 45mg and 90mg for 18 and 10 patients, respectively.  Three patients receiving two 45mg doses were not evaluable based on second fill date.  In summary by weight, 86% (142/166) of patients weighing ≤100kg are estimated to have received an index dose of 45mg and 76% (69/91) of patients >100kg likely received an index dose of 90mg. CONCLUSIONS: The real-world distribution of ustekinumab is consistent with dosing recommendations in the prescribing information.