The Iowa Gambling Task (IGT) is one famous decision making paradigm investigating implicit rule learning.Compared to normal controls, substance abusers were found to perform worse in IGT [Verdejo-Garcia J.,et al,.(2007) Addictive Behaviors], and also showed grey matter deficits in the right dorsal lateral prefrontal cortex (dlPFC) [Yuan K.,et al,.(2010) Neuroscience Letters], However, there is a lack of direct evidence associating IGT performance with grey matter in the frontal brain regions.In the present study, we hypothesized that the grey matter volume of the right dlPFC would positively correlate with the behavior perfornmance of IGT, with larger volume predict better performance.We collected the high resolution Tl-weighted brain images of 19 healthy adults and their functional magnetic resonance images when they performed a modified IGT, in which the original IGT was prolonged and divided into three phases.We found a significant cluster in the right dlPFC by correlating individuals IGT performance with the activation contrast of Phase Ⅰ and Phase Ⅲ.It suggested dlPFC may be related to the learning process to the implicit rule of IGT.Then we calculated the grey matter volume of this cluster using voxel-based morphometry and found it was positively correlated with the IGT performance (r(19) =0.417, P < 0.05, one tailed), with larger volume associated to better performance, which supported our hypothesis.However, the activation of IGT (contrast of Phase Ⅰ and Phase Ⅲ) and the gray matter volume in the right dlPFC were not significantly correlated, suggesting some other factors should be involved and further studied.In conclusion, our results suggest dlPFC plays a important and profound role in implicit rule learning process.