A slide rail assembly comprising: a first rail; a second rail slidably connected to the first rail, the second rail having an opening; a third rail slidably connected to the second rail; a guiding base provided on the first rail, the guiding base having a pair of guiding portions and a stop portion, the guiding portions defining a guiding path and a guiding entrance in communication with the guiding path; a first contact member provided on the second rail, the first contact member comprising a pair of first contact portions and a pair of second contact portions connected to the first contact portions, wherein the second contact portions extend through the opening of the second rail and correspond to the guiding entrance of the guiding base; and a second contact member provided on the third rail, the second contact member having at least one lateral portion corresponding to one of the first contact portions of the first contact member; wherein the guiding path of the guiding base has a first width, the guiding entrance of the guiding base has a second width, and the second contact portions of the first contact member define a third width therebetween; characterised by: the third width being greater than the first width but less than the second width; wherein when the third rail is pulled out from a retracted position relative to the second rail, the lateral portion of the second contact member is pressed against the corresponding one of the first contact portions of the first contact member such that the second rail is displaced simultaneously with the third rail due to the first contact member; and wherein when the second rail is displaced to a predetermined position relative to the first rail, the first contact member abuts against the guiding base, and the second contact portions of the first contact member are guided by the guiding path of the guiding base such that the first contact portions of the first contact member are displaced toward each other, causing the lateral portion of the second contact member to separate from the corresponding one of the first contact portions of the first contact member, thus allowing the third rail to be pulled out and displaced relative to the second rail. a first rail; a second rail slidably connected to the first rail, the second rail having an opening; a third rail slidably connected to the second rail; a guiding base provided on the first rail, the guiding base having a pair of guiding portions and a stop portion, the guiding portions defining a guiding path and a guiding entrance in communication with the guiding path; a first contact member provided on the second rail, the first contact member comprising a pair of first contact portions and a pair of second contact portions connected to the first contact portions, wherein the second contact portions extend through the opening of the second rail and correspond to the guiding entrance of the guiding base; and a second contact member provided on the third rail, the second contact member having at least one lateral portion corresponding to one of the first contact portions of the first contact member; wherein the guiding path of the guiding base has a first width, the guiding entrance of the guiding base has a second width, and the second contact portions of the first contact member define a third width therebetween; characterised by: the third width being greater than the first width but less than the second width; wherein when the third rail is pulled out from a retracted position relative to the second rail, the lateral portion of the second contact member is pressed against the corresponding one of the first contact portions of the first contact member such that the second rail is displaced simultaneously with the third rail due to the first contact member; and wherein when the second rail is displaced to a predetermined position relative to the first rail, the first contact member abuts against the guiding base, and the second contact portions of the first contact member are guided by the guiding path of the guiding base such that the first contact portions of the first contact member are displaced toward each other, causing the lateral portion of the second contact member to separate from the corresponding one of the first contact portions of the first contact member, thus allowing the third rail to be pulled out and displaced relative to the second rail.