Background and Aims: Asthma is a common chronic disease characterized by narrowed airways due to inflammation and muscle constriction. The impact of microorganisms in the environment on asthma is an emerging research area. This literature review focuses on the associations between indoor environmental microbiota of living spaces and asthma/respiratory allergies in Europe. The focus was on studies conducted in the last ten years, utilizing techniques based on dust measurements and including a control group for comparison. Methods: The databases PubMed, Scopus, and GreenFile were searched. Results: We reviewed 490 articles on the basis of title and abstract, of which 12 met our inclusion criteria. Twelve studies met the inclusion criteria, conducted in Finland, France, Sweden, Germany, Austria, Greece, the UK, and one study included ten European countries. Eight studies investigated microbial diversity in children's homes, while four focused on adults. Various sampling techniques, including PCR and DNA sequencing, were used to analyze dust samples. Associations were found between fungal DNA levels in childcare center dust and respiratory symptoms. Higher fungal concentrations were observed in homes with asthmatic children. Indoor humidity and pet presence correlated with microbial agents in mattress dust and asthma outcomes. A total microbial exposure index was proposed as a better predictor of asthma. Asthmatic households had lower microbial richness/diversity. High fungal diversity exposure during infancy inversely related to sensitization to airborne allergens. Conclusions: Further research is needed to establish clinical implications.< Réduire