Tagatose is emerging as a very promising sugar substitute. In this study relative sweetness and sweetness characteristics of tagatose were evaluated and effect of concentration on these characteristics was also tested. The quality of sweetness was judged in terms of overall temporal profile of sweetener, any objectionable taste (bitterness, astringency, chemical-like sensations, etc.) and cooling effect. The relative sweetness and sweetness characteristics were tested through sensory evaluation by panel of experienced judges. The relative sweetness of tagatose was found 0.91. Sweetness characteristics of tagatose were found almost similar to that of the sucrose. The relative sweetness and sweetness characteristics of tagatose were not affected by change in its concentration in the range of 3.3 to 22.0%.