Vector® VIP and ImmPACT™ VIP HRP substrates both produce intense, violet (purple) reaction products, and can be used as alternatives to DAB or as a second color for multiple antigen labeling. Vector® VIP and ImmPACT™ VIP chromogens also provide excellent color contrast in pigmented tissues such as melanoma or retina (1). With the aid of imaging systems and software, the spectral profile of both substrates can be distinguished from other enzyme substrates in applications where antigens are co-localized. Sections stained with either substrate can be viewed by darkfield and electron microscopy. Vector® VIP and ImmPACT™ VIP substrates can be used for both manual and automated staining methods. Stained sections should be dehydrated, cleared, and permanently mounted.