The complexation reaction of trivalent yttrium, neodynium, europium, terbium and yttrbium with bromopyrogallol red, a member of triphenylmethane type of dye in presence and absence of micelle forming cationic surfactant cetyldimethylethylammonium bromide have been studied in detail though number of chromogenic reagents have been reported earlier to form water soluble colored complexes with various rare earths as a binary complexes for their microdetermination. Addition of cationic surfactant, cetyldimethylethylammonium bromide (CDMEAB) sensitizes the color reactions of Y(III), Nd(III), Eu(III), Tb(III) and Yb(III) with BPGR. Formation of water soluble, highly colored ternary complexes with a considerable bathochromic shift in presence of surfactant has been observed. Optimum reaction conditions and other analytical parameters were also evaluated. Stoichiometric ratio 1:2:4 of Ln: BPGR: CDMEAB are responsible for the observed rise in molar absorptivity and sensitivity. Beer’s law was obeyed between 0.81 to 1.81 ppm. Effective photometric range and molar absorptivity of these ternary complexes have been calculated. A simple, rapid and highly sensitive spectrophotometric method has been proposed for the determination of metal ions understudy.