The molecular factors and events that characterize susceptibility and outcome in cutaneous basal cell carcinoma (BCC) have been the focus of much research interest. As a result, we are beginning to understand the complex relationships between exposure to ultraviolet radiation (UVR), host response and the resulting damage to key genes that characterize these tumours. In this review, we will focus on genetic factors that influence susceptibility and outcome. While the search for susceptibility genes has generally resulted in the identification of low penetrance allelic variants, studies on modifier genes influencing outcome variables such as tumour number, age of onset and tumour subtype have identified factors with higher potential impact. Here we will briefly describe some recent work on the genetic basis of the immune response to UVR, the effect of UVR on the generation of reactive oxygen species and their detoxification, and the role of onco- and tumour suppressor genes. Areas for further research are highlighted, together with a consideration of possible applications in clinical practice.