Classical QSAR began almost 30 years ago. This article briefly traces its development, use and impact in relation to drug design and medicinal chemistry. Particular aspects discussed include hydrophobicity, relative potency in a series, tissue selectivity, central nervous system penetration, pharmacokinetics, potency optimization, bioisosterism, mechanistic insights, synthesis termination, receptor mapping, and the design of marketed drugs and late-stage drug candidates. In addition, some recent QSAR studies and examples of the use of the Free-Wilson approach are reviewed.