The admission and assessment of patients for elective procedures is a task faced by all healthcare organisations that provide elective surgical services. Several different strategies have been used to facilitate the management of these tasks. Nurse-led preadmission clinics or services have been implemented in many health services as one of these management strategies; however their effectiveness has not been established. The objective of this review was to examine the available research on the effectiveness of nurse-led elective surgery preoperative assessment clinics or services on patient outcomes. Types of participants The review considered studies that included adult or paediatric patients who were undergoing any type of elective surgical procedure, either as a day-only case or as an inpatient.Types of interventions The review considered studies that evaluated the effect of attending or receiving the services of a nurse-led elective surgery outpatient preadmission or preoperative assessment clinic.Types of outcomes This review considered studies that included the following outcome measures: length of stay, cancellation of surgery, incidence of non-attendance for scheduled surgery, mortality, morbidity, adverse surgical events, preoperative preparation, recognition and fulfilment of postoperative care needs, patient anxiety and reducing the number of overnight stays for day or ambulatory surgery patients.Types of studies The review considered any randomised controlled trials published after 1999; in the absence of RCTs other research designs, such as non-randomised controlled trials and before and after studies, were considered for inclusion in a narrative summary to enable the identification of current best evidence regarding the effectiveness of nurse-led preoperative assessment services. This review excluded studies of preoperative education as this has been the subject of a previous review. We also excluded studies of emergency admissions. Additionally, studies comparing nurse-led with physician-led preadmission assessments were excluded as that has also been the subject of a previous systematic review. The search strategy aimed to find both published and unpublished studies. A three-step search strategy was utilised in each component of this review. An initial limited search of MEDLINE and CINAHL was undertaken followed by analysis of the text words contained in the title and abstract, and of the index terms used to describe articles. A second search using all identified keywords and index terms was then undertaken across all included databases. Thirdly, the reference list of all identified reports and articles was searched for additional studies. Papers selected for retrieval were assessed by two independent reviewers for congruence to the review's inclusion criteria, using a tool developed for the purpose. Methodological validity was assessed by two reviewers prior to inclusion in the review using standardised critical appraisal instruments from the Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI). Data were extracted from papers included in the review using the standardised data extraction tool from JBI-MAStARI. Due to the methodological heterogeneity of the included studies, no statistical pooling was possible and all results are presented narratively. Of the 19 included articles, there were 10 audits of patient and hospital data, 3 surveys or questionnaires, 3 descriptive studies, 1 action research design, 1 prospective observational study and 1 RCT. Five of ten studies reporting data on cancellations rates found that nurse-led preadmission services reduced the number of day-of-surgery cancellations. Non-attendance for surgery was also reduced, with nine studies reporting decreases in the number of patients failing to attend. Eight studies reporting data on patient or parent satisfaction found high levels of satisfaction with nurse-led preadmission services. Three of four studies investigating the effect of the nurse-led preadmission service on patient anxiety found a reduction in reported anxiety levels. Three studies found that preoperative preparation was enhanced by the use of a nurse-led preadmission service. While all included studies reported evidence of effectiveness for nurse-led preadmission services on a wide range of outcomes for elective surgery patients, the lack of experimental trials means that the level of evidence is low, and further research is needed. Nurse-led preadmission services may be an effective strategy for reducing procedural cancellations, failure to attend for procedures, and patient anxiety, however currently the evidence level is low. Currently the overall level of evidence regarding nurse-led preadmission services is low and further more rigorous studies are required for all the examined outcomes. There is little evidence regarding the effect of this intervention on length of stay, mortality rates and morbidity, and therefore more research is needed on the effect of nurse-led preadmission services on these important outcomes.