The current pandemic has highlighted the importance of hand hygiene as a preventive measure to avoid the transmission of diseases. It is a habit that should be reinforced during childhood, so that it lasts into adulthood. The main objective was to analyse and describe, through drawing, the mental schemas that 6-12 year-old pupils have about clean and dirty hands and their relationship with microorganisms. A descriptive and qualitative study was carried out with 260 participants in which their drawings were analysed according to thecategories: colouring, shape and/or presence of wounds, viruses or living beings, localisation and presence of accessories. The results show that dirty hands are represented coloured in sections combining various shapes and, in some cases, living beings or viruses can be found. Among 11-12 year-old students there are very few cases where dirt is represented as dots or reference is made to microscopic size, with neutral and warm colours being the most used. Clean hands are represented by the silhouette of the hand in a single colour. Sometimes accessories are added to reinforce the idea of cleanliness and it is not conceivable that a clean hand could harbour microorganisms or dirt.