Despite a relatively successful conservation programme for the endangered one-horned rhinoceros in the National Parks of the Terai region, poaching remains one of the major threats to its survival in Nepal. In recent years, there has been an alarming rise in the number of rhinos poached; over 100 rhinos were taken in and around the Royal Chitwan National Park (RCNP) between 1998 and 2003. Although rhino poaching levels are influenced by the price of rhino horn on the international black market (amongst a host of other socio-economic factors), there have not been any attempts to study the reasons behind poaching in Nepal using econometric models developed and applied elsewhere. This study uses econometric models to explain changes in the level of poaching in the RCNP over a 30-year period. Factors that are thought to influence the number of rhinos poached in the RCNP include: (i) rhino population; (ii) effectiveness of anti-poaching measures; (iii) penalties for poaching; (iv) availability of alternative economic opportunities (i.e., opportunity costs of poaching); and (v) the price of rhino horn. The results indicate that anti-poaching units (APUs), in their original organisational and operational form were highly successful in controlling the level of poaching in the RCNP. Furthermore, the availability of local economic opportunities seemed to reduce the level of poaching significantly. However, the penalties imposed on the convicted poachers were found to have little or no effect on the level of rhino poaching in the RCNP. The results also indicate a sharp rise in the number of rhinos poached during the years of the Maoist insurgency in the country, compared to the years before. Although the analysis is still very simplistic, it provides valuable insights into the factors that have affected the level of poaching in the RCNP over the years. It is hoped that these insights will be helpful in formulating effective policies to tackle rhino poaching, especially in and around the RCNP where Nepal’s largest population of one-horned rhinoceros is found.