A computerized near-threshold fatigue crack growth rate (FCGR) test method has been applied at cryogenic temperatures. Near-threshold FCGR tests were conducted at room and cryogenic temperatures as low as 4.2 K (−452°F) on JBK-75 (modified A-286) stainless steel (base and autogenous gas-tungsten arc weld metal). Near-threshold crack growth rates in both the base and weld metal tended to decrease with decreasing temperatures from 297 to 4.2 K (75 to −452°F). At each temperature, the JBK-75 base material typically demonstrated a higher threshold stress intensity range than the weld material. Unlike the room temperature results, at 77 and 4.2 K (−320 and −452°F) near-threshold crack propagation rates were insensitive to load ratio (R = P_min/P_max). The decreased dependence of near-threshold FCGR data on load ratio at low temperatures appears to be in agreement with a crack closure model.