Background Acute myocardial infarction (AMI) incidence has been declining throughout the developed world. Australia has been an outlier to this trend, with AMI incidence reportedly increasing. This study provides a detailed investigation on the incidence of acute myocardial infarction (AMI) in Western Australia overall, and by age, sex, level of geographic remoteness and socioeconomic status. Methods Individual level data was sourced from routinely collected hospital admissions and the Western Australian mortality register, providing coverage of the entire population. Hospital admissions were grouping into continuous inpatient stays to avoid double counting individual AMIs. The mortality register provided coverage of out of hospital AMI deaths. Results AMI incidence decreased in Western Australia from 1993 to 2012 by 1.2% per year (95% confidence interval (CI): − 1.7 to − 0.8). This decrease was concentrated in the 50–80 age group, with rates for those under 50 and over 80 remaining stable. AMI rates increased in both regional (Annual percentage change (APC), 95% (CI): 4.7, 3.7 to 5.7) and remote areas (APC, 95% CI: 4.6, 3.5 to 5.6). There was a large effect of socioeconomic status, with those from the lowest quintile having a 68% higher AMI incidence than those from the highest socioeconomic quintile. Conclusions These results are generally in line with other developed nations. Previous findings of increased incidence Australia-wide appear likely the result of double-counting AMIs within hospitals, and excluding out of hospital deaths. Further focus is required on particular subpopulations showing increased incidence of AMI, such as those in regional and remote areas. Focus on primary care prevention of cardiovascular risk factors will likely be the most effective method to ensure reductions in AMI incidence in these populations.