OBJECTIVE: Biologics have the most favorable clinical profile required for the management of moderate to severe psoriasis. However, costs and patients' adherence related to biologics are important factors to consider while making informed decisions regarding the biologics therapy in psoriasis management. This study examined predictors of biologics related adherence, total health care costs, and service utilization among psoriasis patients enrolled in Medicaid program. METHODS: This was a longitudinal cohort study of psoriasis patients (<65 years old) enrolled in North Carolina Medicaid who were prescribed one of the biologics (alefacept, efalizumab, and etanercept) approved by the US Food and Drug Administration during the study period. Patients' medication adherence, total health care costs, and service utilization (hospitalizations, inpatient and outpatients visits) patterns in pre- and post-biologics period were examined. RESULTS: Adherence to biologics was significantly higher as compared with the other psoriasis medications (0.66 vs. 0.39; P<0.001). Prescription drug costs was significantly higher in the post-biologics period ($3796.77 vs. $11706.32; p<0.001). However, total health care costs in the post-biologic period did not differ significantly from pre-biologic period ($14662.22 vs. $16156.1; p>0.05). Patients' adherence and health care costs did not differ significantly across biologics. After controlling for other variables, patients had significantly lower number of hospitalizations in the post-biologic period (p<0.001). Adherence related to psoriasis medications (biologics and other psoriasis medications) remained the strongest predictors of number of ED visits in the study cohort (both p<0.001) CONCLUSIONS: Although costs associated with biologic prescriptions were higher, total health care costs did not differ significantly in the post-biologics period. Biologics had a better adherence rate as compared to other psoriasis medications. Increased medication adherence was associated with a lower number of ED visits. Further investigations using larger cohorts are warranted to better understand economic and patient-reported outcomes associated with biologic treatment in psoriasis.