In this paper, the sensitivity of three-dimensional fluorescence spect
rometry (TDFS) is studied by using the total fluorescence intensity, c
alculated by Monte Carlo integration, instead of conventional single-p
oint intensity. It has been proven that the sensitivity of the total f
luorescence intensity method is nearly one hundred times better than t
hat of the single-point intensity method for the determinations of flu
orescein and tryptophan. The mechanism of the method has also been stu
died. Index Headings: Fluorescence; Three-dimensional fluorescence spe
ctrometry; Chemometrics; Monte Carlo techniques; Monte Carlo integrati
on; Fluorescein; Tryptophan.