• Here we discuss the clinically-relevant features of a class of Eukaryotes known as Fungi. Fungal infections are known as mycoses and their study is termed "Mycology". Mycoses are grouped according to the depth to which they can invade into human tissues. In general, the human immune system is highly adept at eliminating fungal infections and in immunocompetent individuals very little invasion beyond the skin and mucous membranes is possible. Systemic fungal infections almost exclusively occur in those with compromised immunity.