Abstract: A grain probe consists of an elongate hollow tube. The tube has a solid nose with a tapered end and a helical rib on its outside surface. The rib has a short radial extent, considerably less than the diameter of the tube. Immediately following the helical rib is a sampling valve with a sample opening in the side wall of the tube. This is covered by a valve sleeve that slides between a closed position covering the opening and an open position engaging the end of the helical rib. The valve is retained in the closed position by a cut-out in the end of the sleeve engaging over a stud projecting from the wall of the tube. The cut-out is L-shaped and oriented so that rotation of the tube to drive it into grain will keep the stud engaged in the cut-out. The valve sleeve may carry ribs projecting into the surrounding grain to ensure that when the cut-out and stud are disengaged, the sleeve will remain stationary in the grain while the tube moves to open the sample opening.