Sample preparation is one of the most challenging tasks in laboratories, particularly in what concerns biological specimens, since they cannot be directly analyzed. A considerable amount of time and effort is spent in the extraction of the analytes and their concentration in a solvent that is compatible with analytical instrumentation. Several approaches can be used for this purpose, and one of the most used worldwide is LLE. This article outlines how the miniaturized approach of LLE - liquid-phase microextraction - was developed. The different types of liquid-phase microextraction and their applications are also discussed.