The differences in values, accuracy, reproducibility and interdevice variability of three models of portable peak flowmeters (standard and low range of Assess, mini-Wright, Pulmo-Graph) before use and after they had been used 1000 times. A computerized standard flow generator was used to evaluate. Standard range; The three models showed differences in values before and after 100 uses of less than 3 percent at flow rates below 480 L/min. However, the used flowmeters, especially the Assess, showed higher values compared with the new ones at higher flow ranges. There was no significant difference in accuracy between the new and used mini-Wright and Pulmo-Graph models. The used Assess, howevers, showed higher values at higher ranges, thus demonstrating improved accuracy over the new ones. The reproducibilities of the three models deteriorated at high flow rates. The interdevice variability of the used Pulmo-Graph flowmeter was better than that the new one. No significant changes were observed in the mini-Wright, while the Assess showed deteriorated interdevice variability. Low range; The three models showed no significant differences in values, accuracy, reproducibility or interdevice variability before and after use.