To identify barriers faced by Aboriginal people from remote communities in the Northern Territory (NT) when accessing hospital-based specialist medical services, and to evaluate the impact of the Specialist Outreach Service (SOS) on these barriers. Combined quantitative and qualitative study. Remote Aboriginal communities in the "Top End" of the NT, 1993-1999 (spanning the introduction of the SOS in 1997). 25 remote health practitioners, patients and SOS specialists. Numbers of consultations with specialists; average cost per consultation; perceived barriers to accessing hospital-based outpatient care; and perceived impact of specialist outreach on these barriers. Perceived barriers included geographic remoteness, poor doctor-patient communication, poverty, cultural differences, and the structure of the health service. Between 1993 and 1999, there were 5,184 SOS and non-SOS outreach consultations in surgical specialties. Intensive outreach practice (as in gynaecology and ophthalmology) increased total consultations by up to 441% and significantly reduced the number of transfers to hospital outpatient clinics (P< 0.001). Average cost per consultation was $277 for SOS consultations, compared with $450 at Royal Darwin Hospital and $357 at the closest regional hospital. Outreach has reduced barriers relating to distance, communication and cultural differences, and potentially bolsters existing primary healthcare services. When compared with hospital-based outpatient services alone, outreach is a more accessible, appropriate and efficient method of providing specialist medical services to remote Aboriginal communities in the NT.