Many work activities include hazards to workers, and among these biological risk is particularly important, mostly because of different types of exposure, contact with highly dangerous agents, lack of limit values able to compare all exposures, presence of workers with defective immune systems and therefore more susceptible to the risk. Bioaerosols and dust are considered important vehicles of microganisms at workplaces and interaction with other occupational agents is assumed. Moreover, biological risk can be significant in countries with increasing economic development or particular habits and some biological agents are also classified as carcinogenic to human. Specific emerging biological risks have been recently pointed out by Risk Observatory of the European Agency for Safety and Health at work, and we must consider the worker's attitude and behaviour, influenced by his own perception of risk more than his real knowledge, that could over-underestimate the risk itself. Therefore, biological risk at work requires a complex approach in relation to risk assessment and risk management, made more difficult due to the wide variety of biological agents, working environments and working techniques that can determine the exposures.