Recently, convergence of diagnosis, drug delivery and real-time noninvasive therapeutic monitoring took place (within the big pharma company) that leads to creation of the word “theragnosis” for the implementation of these three distinct pursuits simultaneously. This chapter envisions the use of the multifunctional oil-in-water (o/w) nanosized emulsions (NE) that carries imaging agents, anticancer or lipid lowering or antiatherosclerotic drug molecules and homing devices together for simultaneous imaging/diagnosing and treatment of cancer and atherosclerosis. A complete outline is given on the formulation of drug-loaded NE together with active and passive targeting moieties for accessing the unreachable organs present inside the human body. In order to make a better nanosized drug targeting systems for reachable and unreachable organs/parts of the body and thus, permitting the target place-precised drug delivery and/or improved drug bioabsorption, the NE is classified into three generations based on the research conducted over the previous 20 years.