Eighteen temperature sections were obtained during August 1977 using expendable bathylthermograph probes along a 110 km tract oriented perpendicular to the mean direction of the Gulf Stream off Onslow Bay. Concurrent velocity and temperature measurements were obtained beneath the Stream from an Aandera current meter moored 48 m above the bottom (620 m depth). The measurements revealed the passage of a Gulf Stream meander with a period of approximately 5 days, vertical changes in isotherm level as large as 200 m, and a lateral meander amplitude of approximately 39 km as defined as the 16¿C isotherm at 200 m. A study of the meander amplitude as a function of depth is caried out in terms of the migration of the sloping frontal surface. The envelope of frontal migration is defined by curves which are found to approximate the bottom slope down to the 'knee' in the bottom topography at 700 m. The peak-to-peak meander amplitude decreases from 39 km near the sea surface to 26 km at a depth of 700 m, which suggests that the meander process off Onslow Bay is not confined to the upper slope. A strong correlation exists between the current and temperature field at the moored near-bottom sensor and frontal migration of the 200 m level with the overall impression that the mender process has an extensive horizontal correlation scale, comparable to the width of the Gulf Stream. A downstream phase speed of 25 cm/s is derived for the meander based on a relationship between characteristics of the temperature field and characteristics of the velocity field.