Diclofenac sodium (DS) is a non-steroid anti-inflammatory drug (NSAID) and is the most prescribed for the treatment of pain and inflammatory diseases. Like all NSAIDs, DS exerts its effects by inhibiting prostaglandin synthesis by blocking COX-1 and COX-2 enzymes [1, 2]. Indications for use include rheumatic disease, migraine, musculoskeletal and postoper- ative pain. It is also used for actinic keratosis, peripheral and postoperative inflammation and ophthalmic seasonal allergic conjunctivitis. It has been associated with opioid protective effects in the treatment of cancer pain. DS is very well absorbed orally, binds to plasma proteins at almost entirely therapeutic levels and has a half-life of about 1-2 hours [1]. Nanoparti- cles (NP’s) are being extensively investigated as drug delivery systems for pharmaceutical applications. The most common- ly used biodegradable polymers in the production of NP’s for modified release are polyglycolic acid, polylactic acid and their copolymers, e.g., PLGA (polylactic-co-glycolic acid) [3]. In this study, DS loaded NP’s with modified release profiles are pre- pared by ‘Double Emulsification Solvent Evaporation Technique’ and their In Vitro characteristic properties are evaluated.