Novel monoalkyl end-capped poly(2-methyl-2-oxazoline) (POXZ-C-12 and POXZ-C-18), with molecular weights varying from 5500 to 8500, were synthesized by the use of the "initiator method", The micellar behavior of these polymers in water was investigated by the fluorescence technique. Critical micelle concentrations are in the range of 0.007-0.4 g L-1 and are dependent on the hydrophilic/lipophilic balance. An aggregation number of 11 was determined for POXZ-C-12. The structural properties of the aggregates have also been investigated by viscometry. Intrinsic viscosities of these polymers have been compared to the ones of poly(2-methyl-2-oxazoline) (POXZ). The POXZ-C-12 aggregates show similar compactness as POXZ precursor chains, whereas POXZ-C-18 aggregates are more expanded. Addition of beta-cyclodextrin (CD) has dissociated the aggregates, and the intrinsic viscosities of the CD end-capped chains have become comparable to the ones of POXZ precursor chains.