Department of Chemistry, University of Allahabad, Allahabad-211 002, Uttar Pradesh, India E-mail: jdpandey@rediffmail.com; drvsanguri@rediffmail.com Department of Chemistry, Kamla Nehru Institute of Science, Sultanpur-228 118, Uttar Pradesh, India Manuscript received 23 August 2007, revised 10 April 2008, accepted 17 June 2008 The present work is concerned with the theoretical analysis of quite new and rare data on viscosity of a regular quinary and its quaternary subsystems at 308.15 K and 313.15 K (Nhaesi and Asfour, J. Chem. Eng. Data, 2005, 50, 149). For the first time, six different relations, viz. Wassiljewa relation, Sutherland-Wassiljewa (S-W) relation, Arrhenius model, Bingham relation, Kendall-Munroe (K-M) relation and Croenauer-Rothfus-Kermore (C-R-K) relation have been applied to the quinary system (toluene + octane + ethylbenzene + tetradeeane + hexadecane) and its quaternary subsystems. The theoretical results are compared with experimental viscosity data reported in the aforementioned papers. Quite interesting results are obtained.