The tiger pufferfish Takifugu rubripes is one of the most valuable aquaculture species in Japan. In this study, we investigated the genetic variation in resistance to heterobothriosis caused by a host-specific monogenean parasite, Heterobothrium okamotoi, in the tiger pufferfish, and examined the possibility of selective breeding for enhancing resistance traits. A total of 299 tiger pufferfish produced from ten males and one female caught from the wild were experimentally exposed to oncomiracidia of H. okamotoi. The number of parasites on the gills at 3 weeks post-infection ranged from 0 to 68, with great variation observed both within and between families. The estimated heritability for parasite density was small, but significantly different from zero (H-2=0.098; 95% confidence interval: 0.025-0.201). Although we may have sampled a limited fraction of the genetic variance as the number of families was small, the results suggest that there are genetic components that affect heterobothriosis resistance in the species. A positive phenotypic correlation was observed between parasite count and standard length (r=0.66). Further investigation of the genetic correlation between the two traits using larger families is needed to assess the impacts of selective breeding on heterobothriosis resistance in this species.