This paper presents findings from a national study of the Irish public health nursing service and focuses, in particular, on issues relating to service configuration. The findings are drawn mainly from a national questionnaire of public health nurses (PHNs) working with families with infants (n=613; response rate 54 per cent) and the data were gathered in 1999/2000. The average ratio of public health nurse (PHN) to population size was found to be 1:3997 with a range between 500 and 16,500. The vast majority of respondents (85 per cent) had responsibility for five or more client groups including the elderly, those requiring clinical nursing care, terminal nursing care, psychiatric care, school nursing and the organisation of the home help service. Statistically significant differences between and within health board areas in the extent to which other nurses were available to the service led to a conclusion that in these circumstances a standardised service across individual PHN areas is not possible. The findings highlight the importance of the principle of vertical equity where service configuration is determined by population composition and need.