The majority of research in genetic diversity yields recommendations rather than actual conservation achievements. We assessed the efficacy of actual in situ and ex situ efforts to conserve Parashorea chinensis (Dipterocarpaceae) against the background of the geographic pattern of genetic variation of this species. Samples from seven natural populations, including three in a nature reserve, and one ex situ conservation population were studied. Across the natural populations, 47.8% of RAPD loci were polymorphic; only 20.8% on average varied at the population level. Mean population genetic diversity was 0.787 within natural populations and 1.410 for the whole species. Significant genetic differentiation among regions and isolation by distance were present on larger scales (among regions). AMOVA revealed that the majority of the among-population variation occurred among regions rather than among populations within regions. Regression analysis, Mantel test, principal coordinates analysis, and cluster analysis consistently demonstrated increasing genetic isolation with increasing geographic distance. Genetic differentiation within the region was quite low compared to that among regions. Multilocus spatial autocorrelation analysis of these three populations revealed random distribution of genetic variation in two populations, but genetic clustering was detected in the third population. The ex situ conserved population contained a medium level of genetic variation compared with the seven natural populations; it contained 77.1% of the total genetic variation of this species and 91% of the moderate to high frequency RAPD fragments (f > 0.05). Exclusive bands were detected in natural populations, but none were found in the ex situ conserved population. The populations protected in the nature reserve contained most of the genetic variation of the whole species, with 81.4% of the total genetic variation and 95.7% of the fragments with moderate to high frequency (f > 0.05) of this species conserved. The results show that the ex situ conserved population does not contain enough genetic variation to meet the need of release in the future, and that more extensive ex situ sampling in natural populations TY, NP, HK, and MG is needed. The in situ conserved population contains representative genetic variation to maintain long-term survival and evolutionary processes of P. chinensis.