Islands are especially susceptible to the loss of indigenous species following anthropogenic change. Although tourism has long been cited as a justification for conserving biodiversity via the establishment of national parks and reserves, it also contributes to biodiversity loss as a result of direct habitat change and human activities, as well as more indirectly via the introduction of exotic species and environmental change. An island biogeographical approach is used to provide an exploratory analysis of tourism and biodiversity relationships in the Caribbean and Pacific Islands. Data suggest that the islands are under heavy anthropogenic pressure, of which tourism is just one element, although for some countries tourism represents a substantial real increase in the size of the human population. Few of the countries examined have anywhere near the recommended percentage of area protected, with marine ecosystems being least conserved. The study concludes that there are significant data gaps for examining tourism and biodiversity relations at the national level, but suggests that island biogeographical approaches may yield significant insights into the pressures of tourism on biodiversity at smaller scales if adequate data can be gained.