Investigates the extent and possible causes of variance in property investment valuations for commercial lending purposes within the UK. A literature review was undertaken and a questionnaire survey was circulated to individuals involved in the commercial property valuation process in order to gauge professional opinion. The survey revealed that the main cause of variance was found to be a result of the individual valuer's``behavioural influences''. The survey also found that parties to a valuation instruction widely accept the margin of error principle, the legal manifestation of valuation variance, as a test of negligence.