The flow behaviour of unfractionated poly(methyl methacrylate) (PMMA) (M-w = 1.27 x 10(5)) in acetone and acetonitrite was studied in concentration range 2-12 gm/dl with 2 gm/dl increment, in the temperature range 10-30 degrees C for acetone and 30-45 degrees C for acetonitrile with 5 degrees C interval. Roto-viscometer with NV sensor system was used for this purpose. From the data it was observed that three distinct regions could be seen in shear viscosity (eta) as the shear rate (gamma) was varied from 2.7-245 s(-1). The viscosity was almost constant in the low and high shear rate regions, while in the sheer rate region 12-244 s(-1) viscosity showed a decrease. The zero shear viscosities were calculated by taking the average of first three readings. From this data the critical concentration (C-.), where entanglement occurred, was shown to be above 6 gm/dl.