On an average day in the USA more than 100 Americans die by suicide-half use firearms. Suicide rates overall and by firearms are higher, on average, in states where household firearm ownership is more common. In general this means in states where a greater proportion of the population lives in rural areas. The current ecological study focuses on the relation between measures of household firearm prevalence and suicide mortality in urban areas (metropolitan statistical areas and divisions) using survey-based measures of firearm ownership. Suicide rates (1999-2010) for metropolitan statistical areas that are comprised of large US cities come from death certificate records; rates of household firearm ownership come from the 2002 and 2004 Behavioural Risk Factor Surveillance System. Higher rates of firearm ownership are strongly associated with higher rates of overall suicide and firearm suicide, but not with non-firearm suicide. Stratification by gender, age and race did not materially affect the association between firearms and suicide. This study provides evidence consistent with previous case-control work and extends evidence from previous state- and region-level ecological studies that firearms in the home impose suicide risk above and beyond baseline.