A centrifugal gas/liquid separator for location in a liquid reservoir comprises a generally cylindrical wall defining a separation chamber having a closed end, an open end, an inlet in the cylindrical wall for supplying a gas/liquid mixture into the separation chamber, and a gas outlet located externally of the separation chamber for discharging gases from the separator. The separator defines at least one liquid flow path for conveying separated liquid from the open end of the separation chamber into a reservoir, and at least one gas flow path for conveying separated gases from a radially inner region of the open end of the separation chamber, externally of the separation chamber, to the gas outlet. The separator is particularly suitable for separating air/oil mixtures in an oil system of a gas turbine engine.