In the present book some simple and sensitive spectrophotometric methods for determination of drugs in pharmaceutical formulations and in biological samples have been described. The methods are based on the use of chromogenic reagents, redox reactions, solvent extraction and solid phase extraction techniques. The methods for validation of developed methods have also been described. The drugs for which methods have been described are α-methyldopa, sulphonamide derivatives, lamivudine, nimesulide, nicorandil, olanzapine, and phenothiazine derivatives.