This paper assesses the implementation of the 1986 Gazankulu policy on immunisation in 2 of the homeland's 6 health wards, Mhala and Elim. Vaccination coverage was estimated using the cluster sampling technique recommended by the Expanded Programme on Immunisation of the World Health Organisation. Vaccination coverage of children aged 12-23 months who have received eight valid doses (as stipulated in the programme) is estimated at 25% in Mhala and 53% in Elim (P < 0.001). While both figures can be substantially improved, the analysis concentrates on factors that help explain the differences between 2 districts that fall under the same central administration. As well as demographic differences, key factors include the presence of community-based health facilities and availability of staff (including programme leaders). The need for regional planners to have detailed and comprehensive knowledge of the health system at district level, and to make allowance for this, is put forward as vital to effective health planning. The failure of the Gazankulu policy to attain its objectives also reflects the often unrecognised consequences of the fragmentation of health services.