The research in this chapter investigates both the regulatory and criminological aspects which govern cash and cryptocurrency transactions in criminal activities. The research evaluates whether cryptocurrencies provide better transactional ease than traditional cash for criminal activities. The chapter compares how digital and traditional currencies support different types of crime, including ransomware attacks, money laundering, darknet markets, financial scams, human trafficking, and terrorism funding. What makes cryptocurrencies particularly challenging for law enforcement is that they operate outside the traditional banking system. There is no central authority controlling them, which gives criminals more room to operates. Notwithstanding, the main financial tool for facilitating illicit activities continues to be cash despite the existence of cryptocurrencies. The research further demonstrates that regulatory systems need improvement to handle the increasing threats which stem from criminal activities involving cryptocurrencies. Although cryptocurrencies are increasingly relevant in illegal activity, cash continues to dominate the landscape of illicit finance.