Abstract: Device for regulating a Joule-Thomson effect refrigerator comprising an inlet duct for a refrigerating fluid under pressure to which a choke is connected which opens into an expansion and refrigeration chamber connecting with a passage for heat exchange with the said inlet duct, this choke being regulated to provide a decreasing flow as the refrigeration temperature drops by applying differences in the coefficients of expansion of the components making up the device, characterized in that the said choke, for this purpose, consists in a tubular body (8) connected to the said inlet duct (4) and in which an inner body is held (9, 9a), providing a passage cross-section in it which is regulated by the difference in the coefficients of expansion of the materials making up these two bodies.