Campylobacter jejuni is a major cause of food-borne diarrhea in many countries. However, in some countries, a number of cases were undetected because of the inappropriate detection method and ignorance. Although C. jejuni usually does not cause death in health adults, it can be deadly for immunocompromised persons (Pigrau, et al., 1997). Although thought to be very susceptible in several conditions, C. jejuni in fact is quite prevalent in nature. It can easily cause sporadic cases and outbreaks resulting in economic loss. This review covers three major parts: clinical aspects of Campylobacteriosis, C. jejuni reservoirs and transmission, and methods for detection.