Using an on-line, continuous, single-capillary viscometer and a refractometer in gel permeation chromatography (g.p.c.), two sets of polymer standards (polystyrene and polyisobutene) of narrow distribution and low/median molecular weight were investigated for their intrinsic viscosities. The experimentally obtained intrinsic viscosity versus molecular weight relations of the polystyrenes conform well to the Mark-Houwink-Sakurada (MHS) equation and the Dondos-Benoit (DB) equation in the molecular-weight ranges considered. The deduced viscometric constants were found to be very close to the values reported in the literature. By using both number-average and weight-average molecular weights, the experimental intrinsic viscosity versus molecular weight relations of the polyisobutenes were found to conform to the MHS equation or the DB equation in the molecular-weight range studied. This characteristic of the polyisobutenes provides easy access to the indirect g.p.c. calibration introduced b Dondos.