An uterus is female reproductive tract organ that affected estrus cycle. During a various changes occur at uterus in estrus cycle, one of them is body fluids secretion be called uterine fluid. Therefore, the objective of this study was to investigate the changes of protein patterns using two-dimensional gel electrophoresis in uterus fluids during the follicular and luteal phases in estrus cycle of pigs. In changes of protein spots were confirmed during the follicular and luteal phases. The 136 spots were expressed in follicular phase, the 57 spots of them showed reproducibility. On the other hand, the 140 spots were expressed in luteal phase, the 73 spots of them showed reproducibility. Also, spots expressed in follicular phase were number 69 and 94 spots and spots expressed in luteal phase only were number 156, 157, 184～187, 190 and 191 spots. The spots which of higher expression levels in the luteal phase than in follicular phase were number 76 and 79 spots. In conclusion, the spots expressed in follicular and luteal phases were confirmed with difference levels and these differences are function of RNA resolving, protein synthesis and cytoskeletal architecture.