Hygienic behaviour of the carniolan honeybee (Apis mellifera carnica Pollm) was investigated in 20 localities in Serbia (10 localities from the Machva region and 10 localities from the Rudnik region). The results revealed that the grey bees from Rudnik have a more expressed form of behavior compared to the yellow bees from Machva. The obtained data indicate that colonies of both investigated honeybee varieties, yellow bees from Machva and grey bees from Rudnik, belong to a category of the so called hygienic as the efficiency of elimination of damaged pupae amounted to 91,45% in Machva honeybees and 93,60% in Rudnik honeybees. Our results point to an indisputable relationship between behaviour and the strength of honeybee colonies, i.e. the potent colonies have more expressed behaviour. Both investigated honeybee varieties can be used for improving breeds selection and for organic beekeeping in Serbia, owing to the manifested behaviour and thence, resistance to some diseases (Varroa, American foulbrood, and especially Chalkbrood).