Purpose: To investigate the effect of age of mammography systems on the number of reported faults and equipment downtime. Method: Each screening unit in the NHS breast screening programmes logged any equipment faults in a centralised online fault reporting database. Data on faults occurring in 2018 for digital mammography systems were analysed. The relationship between the age of mammography systems and the number and consequences of equipment faults was examined. Severity of consequences was reported as number of days downtime, and number of cancelled appointments. Results: 2141 reported faults on 432 mammography systems were included in this analysis. The average age of an x-ray set at the time when a fault occurred was 5.76 years. 72% of mammography systems experienced five or fewer faults in 2018. A significant increase was observed in the number of faults and days of downtime reported on mammography systems six years old or greater, compared to those which were five years old or younger at the time the fault occurred (p<0.05 one-tailed, two-sample t-Test assuming unequal variances). A few mammography systems experienced a high number of faults and days downtime within their first year. The highest average number of reported faults and the highest severity of the consequences were found for mammography systems of around nine years old. Conclusions: The data presented could be used as evidence to support guidance on the age at which mammography systems used for breast screening should be replaced.