Thin-layer chromatography (TLC) has been used since the 1960s to analyze and identify lipophilic and hydrophilic compounds in animal parasites and in hosts they infect. Most TLC studies in parasitology have used silica gel as the sorbent, but studies on cellulose and reversed phase plates are also available. TLC has been used both as an analytical and preparative technique to solve problems in parasitology. The parasites should then be washed rapidly in a cold, isotonic solution and prepared for TLC as soon as possible after removal from the host. Blood or hemolymph of cold–blooded animals can be analyzed by TLC to determine the effects of parasitism. Parasites removed from organs or tissues of infected hosts should be processed for TLC as soon as possible. The use of column chromatography is helpful for sample cleanup and fractionation prior to TLC. A variety of methods have been described for quantification of compounds of interest following separation by TLC.