The intensely fluorescent BODIPY (4,4-difluoro-3a,4a-diaza-s-indacene) fluorophore is intrinsically lipophilic, unlikemost other long-wavelength dyes. Consequently, probes incorporating this fluorophore are more likely to mimic the properties of natural lipids. BODIPY fatty acid analogs like BODIPY 500/510 dodecanoic acid (D-3823) and BODIPY FL dodecanoic acid (D-3822) undergo native-like transport and metabolism in cells. They are therefore effective tracers of lipid trafficking, as well as being useful general-purpose membrane probes.