Purpose This paper aims to identify external factors that are critical to the success of estate surveying business in Lagos State, Nigeria. Design/methodology/approach Primary data were collected with the aid of questionnaires from estate surveying firms in the study area. Using a sampling interval computed as 1.93-2, 186 firms were selected from the 359 estate surveying firms based in the study area. The sampling interval required that, after the first selection, every subsequent second estate firm in the group (List) was selected for the survey. Data collected were analysed with the aid of criticality assessment index method such as the Relative Criticality Index and Criterion Criticality Score. Findings The result showed that it was critical for an estate surveying to interdepend with surrounding businesses and maintain good corporate social responsibility for it to succeed. Also, good social relations of the practitioners with the society was found to be an external factor critical to success. In addition, the study found the need to use the advantage of ICT for real estate marketing as an external technological factor for success. It was also found that the economic situation of the immediate locality of the firm and the economic buoyancy of the nation at large influenced both the planning for and the execution of real estate activities of the firm. Research limitations/implications Limiting the findings of the study to external factors alone could subject the findings of the study to bias. Further research targeted at identifying internal factors will provide a balanced view. Practical implications The study will serve as useful tools for existing and upcoming real estate practitioners to chart a performance course for their businesses. It will help estate surveyors to understand what to place more emphasis on if they will succeed in business. Originality/value The findings from this study will provide the estate surveyors and valuers and the professional body with data on things that are critical to their success in business and enhance the practice of real estate management.