Aims This mapping study describes current or planned introduction of assistant practitioner roles in English National Health Service Acute Hospital Trusts. Background In the last decade there has been a growth in nursing support workforce numbers and their scope of practice. An important United Kingdom support worker development is the Assistant Practitioner role. Method A national census was carried out (April 2007) via an emailed questionnaire to Directors of Nursing. Quantitative data were analysed using descriptive statistics. Qualitative data were analysed using thematic analysis. Results Eighty-five per cent (143/168) of Directors of Nursing, from all 10 English Strategic Health Authorities, responded. Forty-six per cent (n = 66) of Trusts had introduced assistant practitioners and 22% (n = 31) were planning to implement the role before 2009. There is wide variation in assistant practitioner numbers across and between Strategic Health Authorities, Trusts and clinical areas. Resistance to the role existed in 32% (n = 46) of Trusts. Reasons for resistance included no perceived need for the role, lack of evidence of effectiveness, financial constraints and professional and patient safety concerns. Implications for nursing management These findings, which contribute to the international evidence-base on health care support workers roles, provide nurse managers with numbers of assistant practitioners and their deployment. This is useful for Nurse Managers making workforce decisions.