Institutional complexity has enjoyed growing attention in the literature on international regimes. However, the concept has not found wide application in the field of human rights research. This article argues that institutional complexity is an important aspect of the international human rights regime, in particular because it may affect the compliance record, impact and effectiveness of international human rights commitments that states enter into. This article analyses the evolution of the prohibition of torture within the Inter-American Human Rights System through the lens of institutional complexity. It proposes that institutional complexity can be captured by two indicators: states' subscription to human rights treaties and their decision density on human rights. Detailed descriptive statistics show the evolution of recommendations, decisions and judgments issued by the judicial and quasi-judicial institutions that operate under the system, and the share of treaty ratifications in the region between 1980 and 2012. The analysis corroborates the theory that the Inter-American Human Rights System has evolved in the direction of greater institutional complexity. This analysis is complemented by an overview of the historical evolution of the institutions created by the regime, with a focus on developments of the Inter-American Commission of Human Rights' mandate over the years.