Rickettsia typhi (formerly named Rickettsia mooseri) is a Gram negative, obligate intracellular bacteria. It is the causative agent of murine typhus or endemic typhus, which has a worldwide distribution, especially in tropical countries. The main vector of murine typhus is Xenopsylla cheopis, a rat flea which maintains Rickettsia typhi in rodents. Many studies have revealed that bacterial S-layers play many roles such as a protective coat, a molecular sieve or as a structure involved in cell adhesion and surface recognition. Rickettsia typhi also posses the S–layers externally to the outer membrane as encoded by slpT gene, which is translated into Crystalline Surface layer protein (SLP). In 1996 Hahn and Chang characterized the SlpT protein of Rickettsia typhi as the protective antigen against murine typhus and also found that it reacted strongly with antiserum of patient with murine typhus. The purpose of this research is to select a part of SlpT of Rickettsia typhi to be cloned. A 400bps piece of SlpT gene encoded for a 10.2 kDa recombinant protein was cloned. After expression and the purification process, this 10.2 kDa protein was examined for antigenicity with murine typhus positive antiserum. The final result showed that this part of SlpT didn’t have enough antigenicity to give a positive reaction with murine typhus antiserum.