A method of condition monitoring of tubing in an injection well, comprising the steps: (a) measuring a first bottom hole pressure response downhole at a bottom hole location in the well and a first wellhead pressure response at a wellhead of the well for a plurality of base injection rates of fluid in the well; (b) determining a friction loss in the tubing between the bottom hole location and the wellhead from the first wellhead pressure response and the first bottom hole pressure response at each of the base injection rates to provide a baseline measurement of friction loss in the tubing against the base injection rates; (c) after a first time period; (d) measuring a second bottom hole pressure response and a second wellhead pressure response for a monitored injection rate of fluid in the well; (e) determining a friction loss in the tubing between the bottom hole location and the wellhead from the second wellhead pressure response and the second bottom hole pressure response at the monitored injection rate to provide a monitored measurement of friction loss in the tubing at the monitored injection rate; (f) analysing the monitored measurement by making a comparison with the baseline measurement to determine any change in friction loss over the first time period; (g) using an increase in friction loss over the first time period as an indicator of deterioration in the condition of the tubing; the method being characterised in that : the second bottom hole pressure response and the second wellhead pressure response are measured at a shut-in of the well, wherein the monitored injection rate is determined from a last injection rate before shut-in. (a) measuring a first bottom hole pressure response downhole at a bottom hole location in the well and a first wellhead pressure response at a wellhead of the well for a plurality of base injection rates of fluid in the well; (b) determining a friction loss in the tubing between the bottom hole location and the wellhead from the first wellhead pressure response and the first bottom hole pressure response at each of the base injection rates to provide a baseline measurement of friction loss in the tubing against the base injection rates; (c) after a first time period; (d) measuring a second bottom hole pressure response and a second wellhead pressure response for a monitored injection rate of fluid in the well; (e) determining a friction loss in the tubing between the bottom hole location and the wellhead from the second wellhead pressure response and the second bottom hole pressure response at the monitored injection rate to provide a monitored measurement of friction loss in the tubing at the monitored injection rate; (f) analysing the monitored measurement by making a comparison with the baseline measurement to determine any change in friction loss over the first time period; (g) using an increase in friction loss over the first time period as an indicator of deterioration in the condition of the tubing; the method being characterised in that : the second bottom hole pressure response and the second wellhead pressure response are measured at a shut-in of the well, wherein the monitored injection rate is determined from a last injection rate before shut-in. <EOS>