OBJECTIVES: To investigate whether additional resources for tertiary cardiology services, aimed at increasing coronary angiography and revascularisation rates, can improve socioeconomic equity of utilisation. DESIGN: Cross sectional ecological study, using the Super Profile classification of enumeration districts and ischaemic heart disease (IHD) standardised mortality ratios (SMR) as a proxy for need. The degree of equity before the provision of extra resources was determined using data for April 1992 to March 1994, and the corresponding picture after, using data for April 1994 to March 1996. SETTING: South Humberside (United Health-Grimsby and Scunthorpe Health Authority, a district of the former Yorkshire Region, before the April 1996 boundary changes). SUBJECTS: Patients with a primary diagnosis of IHD aged > or = 25 years who underwent investigation by angiography, or treatment by coronary artery bypass grafting or percutaneous transluminal coronary angioplasty, as a primary procedure. MAIN RESULTS: In 1992/4, before concerted intervention, both investigation and revascularisation rates, although increasing, were low in Grimsby and Scunthorpe district compared with most other districts in the Yorkshire Region. Also, there was a decreasing trend across Super Profile Lifestyle groups from the Affluent Achievers to the Have-Nots despite a two-fold increase in SMRs indicating the greater need of the more deprived. After appointing a consultant general physician with an interest in cardiology in the Scunthorpe district general hospital in 1994; arranging for both the Grimsby physician and the Scunthorpe physician to undertake angiography at a neighbouring district tertiary cardiology centre in 1995; together with significant additional health authority investment in cardiac procedures in 1995/6, district rates increased considerably, (a 41% increase in investigation and a 47% increase in revascularisation rates). Also, after additional resource input began, the trend for angiographies across socioeconomic groups clearly became more equitable, although increased equity for revascularisations is less apparent. CONCLUSION: Early indications are that additional resources for tertiary cardiology may have reduced socioeconomic inequities in angiography, without being specifically targeted at the needier, more deprived groups. Improvement in socioeconomic equity of utilisation of revascularisation is not yet clear, although data for April 1996 to March 1998 (after a lengthier intervention period) may confirm improved equity. Should this not be so, it might be necessary to specifically target resources to the deprived to increase equity in revascularisation.