Every year, many religious events attended by 300 million pilgrims take place in many holy cities and sites around the world. However, research on municipal solid waste is limited despite the reputation of religious events to generate substantial amounts of waste. This research aims to address this gap and contribute to new knowledge on municipal solid waste management at religious events by investigating and evaluating the municipal solid waste management system applied at the Arba'een event in Kerbala, one of the largest religious events in Iraq. Field observations and in-depth interviews with nine senior managers from Kerbala's municipalities were conducted during the event in 2016, to develop an overall picture of the municipal solid waste management system applied during the event. The data were analysed using thematic analysis and fed to the 'Wasteaware' benchmark indicators framework to evaluate the performance of the event system. The results indicated that the system suffers from operational and governance weaknesses. Despite a focus on municipal solid waste collection and transportation, the collection coverage is only ~ 70%. There is no controlled landfill site in Kerbala. It is estimated that currently ~ 5% of the event municipal solid waste is recycled by informal recyclers: there is no formal recycling scheme. Kerbala does not perform well regarding governance. The inclusivity of providers and users of the municipal solid waste management services is minimal during the event, as the majority of stakeholders are not included in decision-making processes. Municipal solid waste management services are delivered free of charge, thus significantly influencing the financial sustainability of the system. This study recommends that MSW recycling should be encouraged through integrating the informal sector, improving public awareness and introducing a formal recycling scheme to make the event municipal solid waste management system effective and financially sustainable.