Hollow tadpole-like silica particles were successfully synthesized via the microemulsion synthesis method using polyvinylpyrrolidone (PVP), tetraethyl orthosilicate (TEOS), and sodium citrate as starting materials in the presence of isopropanol as a solvent. The effects of TEOS/ammonia (T/A) ratio, PVP molecular weight, synthesis temperature, and sodium citrate concentration on the morphology of particles were investigated. The results demonstrated that synthesis temperature has a vital effect on the morphology of particles. Also, microstructure analysis showed that the length of the silica rods was tunable in the range 1.2-5.2 mu m. Control of the length was obtained by adjusting the synthesis temperature and PVP molecular weight. The transmission electron microscopy results clearly confirmed that the tadpole-like particles were surprisingly hollow and they provided an open side that was completely different from the previous reports. The inner diameter of the silica rods could be adjusted in the range 50-200nm. The existence of such a considerable open side may be practically appreciated in many potential applications such as bio-immobilization.