Plant diseases where more than one pathogen is involved in the infection process are commonly termed as "complex" since their diagnosis and subsequent control are more complicated. A disease complex is produced through a synergistic interaction between two organisms, such as plant nematodes and soil-borne fungi or bacteria. Interactions between nematodes and other pathogens are found on a range of agricultural crops globally. Economically, disease complexes are important because the sum of the damage is greater than the effect of the two organisms causing disease independently. Equally, some diseases (e.g. Verticillium wilt) become more aggressive when nematodes are present, even if the inoculum density is low. Plant nematodes can also act as vectors and carry fungi and bacteria to the susceptible tissue or introduce viruses into the host plant. Overall, the development of a disease complex is influenced by several factors such as the engaged pathogens, their mutual relationship and time of invasion, the host plant species and the prevailing environment. Nematode Disease Complexes discusses the different roles that plant nematodes play in the formation of a disease complex. It provides an account of the agricultural significance, aetiology and epidemiology of important disease complexes and their management strategies based on integration of conventional, current and innovative approaches.