Physico-chemical and pollen analyses were made of unifloral samples of nectar, crop content and honey. The samples were obtained by carrying out cage experiments exclusively with one plant species. The investigations of four plant species are presented:Centaurea montana, Coriandrum sativum. Euphorbia lathyrisandRubus idaeus. During the conversion of nectar to honey its chemical composition changes. The changes in carbohydrate composition cannot be explained by those enzymes described as specific for honey. During the period of time when the bees are working on gathered nectar, the chemical components of the honey, whose origin is the secretion from the bees, is increasing, while the amount of pollen is decreasing. There are negative correlations between the quantity of pollen grains and both enzymatic activity and the amount of proline. With respect to the botanical origin it is suggested that the absolute amount of pollen should be determined and compared with the chemical analysis of the honey.