Moulds are common in our habitat and play significant role in the economy and household. The aim of the article is the indication of selected benefits and threats of moulds present in human environment. The main benefits are: antibiotic synthesis (e.g β-lactam antibiotics production), moulds application in food industry (e.g. mouldy cheese production) and industrial biotechnology (e.g. organic acids synthesis). Threats which are related with moulds presence in our environment are diseases of respiratory system, skin as well as allergies and also possibility of food contamination by mycotoxins synthesized by moulds which can cause animal and people poisoning. The main factors which increase exposure of people to adverse effects of moulds are high moisture, inefficient room ventilation and incorrect storage of resources for food production. Taking care of living quarters technical condition and appropriate control of quality and food storage conditions as well as raw materials for its production, we can reduce undesirable moulds effects.ta.