Organochlorines consist of two different major groups based on their molecular structures, namely, the cyclodiene or diene group and the dichlorodiphenyltrichloroethane group. The analysis of organochlorine pesticides at residue levels can be divided into three parts: extraction, cleanup, and final quantitation. This chapter provides a discussion on each of the three processes on water, sediment, and biota samples. Organochlorines and other organics are effectively removed from water by the carbon adsorption method. Organochlorine pesticides were extracted by passing the water sample through a column of polyurethane foam coated with a gas chromatography liquid phase. Application of supported-bond silicones for the extraction of organochlorines in water was reported by W. A. Aue et al. The extracting materials consisted of thick films of silicones which were chemically bonded to Chromosorb G and consequently unextractable by organic solvents. Solvent extraction using either the separatory funnel or the stirring method is widely used for small samples because of the simplicity of the method.