Some essential oils have strong anti-microbial activity, however they are less effective when they are delivered in vivo. When they enter the body they tend to spread out and do not target the troubled areas. The objective of this study was to try and find an different effective method for microencapsulation and to evaluate the effect of encapsulation on the antimicrobial activity of essential oils in vitro. Several experiments have been carried out in the past years that address these objectives. Some findings from these experiments are essential oils with low water solubility such as carvacrol can be encapsulated with a high loading efficiency by single extrusion method with alginate as the delivering material. Microencapsulation of carvacrol by Ca-alginate did not compromise its antimicrobial activity. Microencapsulation may effectively prevent the loss of essential oils in the upper gastrointestinal tract thus increase the proportion of essential oils delivered to pig intestine. The paper concludes by saying that carvacrol encapsulation is ready to be tested in infected pigs.