This article reviews the experimental steps involved in modern quantitative high performance thin layer chromatography (HPTLC), including sample preparation, application of samples, choice of commercial precoated plates and mobile phases, development of plates, detection and identification of zones, densitometry, and validation of results. Applications of HPTLC-densitometry are discussed and illustrated by the analysis of Capsicum tincture. The cited references provide additional details on methods and instrumentation and numerous applications to particular analytes and sample types.