In this paper, the cranberry (Vaccinium oxycoccus L.) and cowberry (Vaccinium vitis-idaea L.) syrups manufactured using three modified home methods were characterized with regard to their biologically active substances (anthocyanins, polyphenols, vitamin C), as well as to their antioxidant activity and colour (L*a*b*). The modifications in the methods of manufacturing syrups referred to squashing and heating fruit with sugar. Considering the content of the compounds analyzed and colour of the final product, the simultaneous squashing and heating of raw material was found to be the most fitting modification. In the syrups stored, their total phenolic content increased until the fourth month, and the reducing strength, an indicator of antioxidant properties, increased until the eighth month. The content of the remaining compounds, including vitamin C, significantly decreased. Anthocyanins contained in the cowberry passed into the syrups less effectively than those originating from the cranberry, and, also, they faster decomposed during the storage period.