A syringe pump comprises (a) a casing (1,2); (b) within said casing (1,2), a motor (13) (c) an externally screw-threaded drive rod (18) connected at one end thereof to said motor (13) so that, in use, the motor (13) can rotate the drive rod (18) about its axis, the other end (20) of said drive rod (18) being free to rotate in a journal bearing (21); (d) a carriage (22) mounted for sliding movement within said casing (1, 2) and driveably mounted on said drive rod (18) in engagement with the external screw-thread (19) thereof; (e) a strain gauge (17) operatively connected to measure the torque reaction between said motor (13) and said carriage (22) when the carriage (22) acts, in use, against the plunger of a syringe to expel fluid from the syringe; (f) means (7, 8, 10, 11) located externally of the main body of the casing (1, 2) for holding a syringe in position on the syringe pump; (g) means (38, 39) for sensing the position of said carriage (22) with respect to the ends of said drive rod (18); (h) a microprocessor arranged to receive input signals from said strain gauge (17) and said carriage position sensing means (38, 39) and to derive therefrom (when the syringe pump is in use) firstly the fluid delivery rate and secondly the fluid delivery pressure; and (i) a control system, acting through said microprocessor, to input operating commands to the syringe pump.