Moizer (1997) summarises the evidence on audit firm reputation in financial communities, noting that there is considerable evidence that Big Six firms are differentiated from other firms. These audit firms are the same group of firms we refer to as “professional accountancy firms” in the context of their more general role in providing a range of accountancy services. In this paper, we argue that the “reputation effects” described by Moizer (1997) should be found in approaches to company valuation. As Moizer (1997) argues, audit quality is unobservable, but reputation in the financial community can be inferred from market reaction to auditor change, the degree of IPO under-pricing, and the “Big Six” audit premium. However, Sucher et al (1999) argue that reputations are built on the technical and functional quality of service provided, and to a degree this is observable. For this reason, we investigate directly the degree of sophistication of the valuation practices of professional accountancy firms. We use a field study approach centred upon the largest accountancy firms by fee income with a sample of Big Six firms and non-Big Six. As reputation effects can be associated with office location as well as the firm itself (Chan et al, 1993; Brinn et al, 1994; Moizer, 1997), we compare the valuation practices of London and provincial offices within the Big Six sample. Consistent with the predictions of reputation theory, the field studies reveal that the type of valuation analysis used by the London offices of Big Six firms (now Big Five) is more sophisticated than the practices of the non-Big Six firms in general. This paper is based upon research which has been funded by the Institute of Chartered Accountants in England and Wales. We are grateful to Paul Collier, Clive Emmanuel and Simon Keane, and to Ken Peasnell and two anonymous referees for their helpful comments on earlier versions of this paper. The usual disclaimers regarding authors’ responsibility for any errors or omissions apply.