Background Epidemiological data on the occurrence of time-loss injuries over several A-League seasons remains lacking, while the effect of the implementation of ‘Minimum Medical Standards’ as preventive measure needs evaluation.

Objective To explore the preventive effect of the mandatory implementation of ‘Minimum Medical Standards’ in the A-League professional football on the occurrence of total time-loss injuries (and total matches missed).

Design An observational prospective study was conducted over five A-League seasons (2008 to 2013).

Setting A-League professional football.

Patients (or Participants) All professional players from all clubs from the A-League were monitored over five consecutive seasons.

Interventions (or Assessment of Risk Factors) “Minimum Medical Standards” were made mandatory in 2011 in the A-League professional football, relying on appropriate medical testing and employment of medical physicians and physiotherapists.

Main Outcome Measurements Data were collected weekly based on official match previews, official match reviews, official media releases, official websites, and self-report by the players.

Results The number of total time-loss injuries rose from 129 in 2008–2009 to 202 in 2010–2011, decreasing to 162 in 2012–2013 (repeated measures ANOVA not statistically significant). The number of total matches missed rose from 506 in 2008–2009 to 1110 in 2010–2011, decreasing to 542 in 2012–2013. This difference in matches missed over five seasons was found to be statistically significant (P<0.01).

Conclusions The introduction of "Minimum Medical Standards" in the A-League had a favourable effect on the number of total, hamstring, knee and ankle injuries and on the number of matches missed due to these injuries, but not on the number of groin injuries.