In sub-Saharan Africa an almost universal awareness of the serious consequences of AIDS and of the sexual transmission of HIV coexists together with a reluctance in adopting consequent preventive measures, in the form of protected sexual intercourse. The socio-psychological literature on health-related behaviour emphasises the perception of being at risk of HIV infection as being one of the necessary conditions for preventive behaviour to be adopted. Analysing data from the Kenya Diffusion and Ideational Change (KDIC) Project, this paper investigates the determinants of the reported degree of risk perception of getting infected by HIV. In par- ticular, adopting a social interaction approach, we argue that individual risk perception is shaped by social network influences. We use information on ego-centred networks in which individuals are involved in conversations about the risk of getting infected by HIV. We are able to show that the importance of AIDS related knowledge and behavioural factors risk to be mis-estimated if one neg- lects the role of individualsí reciprocal influences. We conclude that risk perception is as much a product of individual character- istics and behavior as it is a collective feeling shared among interacting individuals. Results suggest that in our study men are more susceptible than women to network influence.