Restart pressures for a gelled crude oil were determined experimentally for three pipes with a length of 5.8 m and diameters of 28 mm (1 in.), 55 mm (2 in.), and 82 mm (3 in.). A comparison of extrapolated restart pressure values based on data from a 4.3 mm (0.17 in.) pipe using the same oil was performed. The objective was to investigate the relation between the restart pressure of a gelled crude oil and the pipe diameter used to determine the yield stress used for extrapolation to larger pipe diameters. It was shown that the restart pressure was not proportional to the pipe diameter and that yield stress values obtained from small pipe diameters will overpredict the restart pressure compared to experimental values for larger pipe diameters. As a consequence, extrapolation of restart pressures based on small diameter pipe experiments may lead to very conservative estimations of restart pressure.