The microviscosity of micelles of the dimeric (gemini) surfactants alkanediyl-alpha,omega-bis(dimethyldodecyl-ammonium bromide), referred to as 12-s-12 (s = carbon number of the alkanediyl spacer), has been obtained from measurements of the fluorescence anisotropy of micelle-solubilized diphenylhexatriene (DPH) and of the intensity ratio I-M/I-E of micelle-solubilized dipyrenylpropane (P3P, I-M and I-E = intensities of the monomer and excimer emissions). The micropolarity of these surfactant micelles was characterized by the value of the fluorescence intensity ratio I-1/I-3 Of the first and third vibronic peaks in the emission spectra of micelle-solubilized pyrene. The microviscosity and micropolarity of the trimeric surfactant 12-3-12-3-12 and of the tetrameric surfactant (12-3-12-4-12-3-12) micelles have also been determined in order to gain information on the effect of the degree of oligomerization of the surfactant. The microviscosity and micropolarity of the asymmetric two-chain surfactants, the dimethyldodecylalkylammonium bromides, referred to as 12-s/2 (s/2 = carbon number of the variable alkyl chain varying from 1 to 10), which can be considered as the monomers of the 12-s-12 surfactants, have been determined for the sake of comparison. The I-1/I-3 vs s plots for the 12-s-12 and 12-s/2 series were found to be coincident, except for s = 2, revealing that the polarity sensed by pyrene in its micellar solubilization site is not affected by the "dimerization" of the surfactant. The micropolarity goes through a maximum for the two series of surfactants as a result of the change of location of the spacer or variable alkyl chain as s is increased. The microviscosity in the 12-s-12 series decreased rapidly as s increased above 3, then more slowly, and leveled out, but was nearly independent of s in the 12-s/2 series, in the range s/2 = 1-8. For the two series of surfactants the microviscosity decreased upon increasing temperature but increased when the micelle shape of the surfactant oligomer micelles changed from spherical to elongated. Also, the microviscosity increased significantly and nearly linearly with the number of dodecyl chains in going from DTAB to the dimer, trimer, and tetramer. These results are used to explain the low values of the quenching rate constants characterizing micellar solutions of surfactant oligomers and hydrophobic microdomains in solutions of water-soluble amphiphilic polymers (polysoaps), with respect to micelles of the corresponding monomeric surfactants.