The pressure dependence of the critical consolute temperature in nitrobenzene-hexane mixture has been studied in the -28 to + 110 MPa range. The negative pressure part of the locus was determined by the extrapolation of the pretransitional anomaly of nonlinear dielectric effect and analyzed by a modified Simon-Glatzel type equation, which makes the extension into the P < 0 domain possible. This equation is parameterised by invariant coefficients and exhibits a negative power exponent. Our results proved that fluctuations can be important even far away from the critical consolute point. (c) 2007 Elsevier B.V. All rights reserved.