This paper reviews applications of partitioning tracers in the petroleum industry. Partitioning between phases slows the partitioning tracers in a phenomenon known as chromatographic retardation, from which fluid saturations and surface properties can be deduced. Single-well tracer testing (SWTT) to determine residual oil saturation to waterflood, S-orw, is the most common application of partitioning tracers. More than 200 tests have been run since its invention in 1971. In addition to development of new simulators, a mass-balance method and an internally calibrated method were proposed for direct calculation of S-orw from the tracer reaction rates. With the introduction of the chromatographic transformation technique, several successful interwell tests to determine residual oil saturations in watered-out and gas-saturated reservoirs have been reported. The technique involves direct comparison of the partitioning and nonpartitioning tracer profiles with no need for simulation. In a different approach, full-field simulation of a multiwell test has also been used to estimate oil saturation distribution. Other interesting applications include in-situ miscibility measurement, determining trapped gas saturation during a foam flood, relative permeability ratio measurement, and direct logging of gamma-emitting partitioning tracers through casing to determine residual oil saturation, S-or, vertical distribution.