The Food and Drug Administration (FDA or Agency) is announcing the availability of a draft guidance for industry entitled “Assessing the Irritation and Sensitization Potential of Transdermal and Topical Delivery Systems for ANDAs.” This draft guidance provides recommendations for the design and conduct of studies to evaluate the in vivo skin irritation and sensitization (I/S) potential of a proposed transdermal or topical delivery system (collectively referred to as TDS). The recommendations in this draft guidance relate exclusively to studies submitted in support of an abbreviated new drug application (ANDA).