One of the largest wild populations of the highly endangered Indian rhinoceros (Rhinoceros unicornis) resides in and around Royal Chitwan National Park (RCNP) in Nepal. Unfortunately, rhino poaching in the park has increased dramatically since 1998. This paper presents a demographic model of the Royal Chitwan rhino population to describe the effect of poaching on the population, explore the validity of a decreasing carrying capacity in the park, and provide input to an overarching bioeconomic model. We used a simple, logistic-style model to describe the rhino population. Starting with values available from the literature, three sets of best-fit parameter values were chosen. We then used these three model variations to indicate the size the RCNP rhino population would have been had the extensive poaching between 1998 and 2003 not occurred. All three model variations suggested that the current rhino population was below the park’s capacity and revealed the strong negative impact of poaching. These results supported the vital importance of continued anti-poaching efforts in Royal Chitwan.