Southeast Asia, which includes the emerging economies of Brunei, Cambodia, Indonesia, Lao PDR, Malaysia, Myanmar, the Philippines, Thailand and Vietnam as well as the developed economy of Singapore, represents one of the most rapidly growing regions globally. Entrepreneurship has played a major role in this impressive growth. According to the Global Entrepreneurship Monitor, the population of these countries shows an above average intention to become entrepreneurs. But in spite of impressive economic growth and entrepreneurial activity, there have been very few studies on the impact of business angel (BA) financing. This lack of research arises because many BAs operate in the informal economy and hence prefer a low profile, making them even more invisible compared to their Western counterparts. In the chapter the author reviews the studies that have been conducted on the BA markets in Southeast Asia. He argues that BAs in Southeast Asia exhibit differences as well as similarities to their counterparts in Western economies. There are apparent similarities as most BAs are experienced and hands-on investors, actively use their networks and co-invest with other BAs. However, there are obvious differences, notably in terms of the absence of a fully developed institutional framework to support BA investing. Singapore is the exception in this respect with a business environment supported by well-developed institutions. The response of many BAs is to focus more strongly on family relationships, and be more socially focused in their investment strategy. An additional issue raised by the author is the definition of BAs. The traditional way of defining a BA seems to fit, except in Thailand and for the Chinese Filipinos who make what are more family-like investments. This raises concerns about the definition of a BA in studies that are conduced outside Western countries.