Background: A search strategy for a systematic review is intended to identify all relevant articles for a well focussed question. Searching for public health interventions is more complicated than searching for medical studies since the subject draws from a range of disciplines and related sources of research evidence. We are currently carrying out a review on inter-agency collaboration for the newly formed Cochrane Public Health Review Group (CPHRG). An inclusive search of a very wide range of sources is logical, but time consuming. Is it necessary? Objectives: To carry out analysis of each information source used in the review, assess its contribution and its potential value for other reviews within the subject area. Methods: We will evaluate the performance of the search strategy published in the protocol. This consisted of a search of 25 databases with a comprehensive list of search terms. ‘Snowballing’ methods were also used including expert contact, website searching and reference list follow up. We will identify how many relevant studies were generated using electronic databases compared to each snowballing method. For each individual database we will measure the total number of papers retrieved by the search strategy and the relative contribution to those papers selected for full-text retrieval (based on title and abstract). We will also measure whether any of the papers selected for full-text retrieval were unique to a particular database or snowballing source. Results: A comparison will be drawn between the number of total hits (19,108) and the number of potentially eligible articles contributed, incrementally, by each information source. We will report on the impact of including a wide range of databases on the final number of included studies. Conclusions: This analysis will contribute to the guidance available to authors embarking on a systematic review of a public health intervention and considering which information sources to include.