This article sheds light on the rhetoric of cross-cultural letters of request in the Thai business context. The focus is on the contrastive analysis of 80 authentic letters of request written in English by Thai speakers and native English speakers. The corpus consists of 38 Thai (TH) letters, and 42 Non-Thai (NT) letters. The cross-cultural variation is investigated both quantitatively and qualitatively from the perspectives of contrastive text linguistics and pragmatic. The quantitative analysis explores the lengths of the TH and NT letters in relation to the distribution and position of requests. Contrastive text linguistics was used in this study to examine the rhetorical structures (e.g. structural representation) in letters of request and their linguistic realisations (e.g. linguistic features). From a pragmatic perspective, the analytical focus was on persuasive strategies (i.e. rhetorical appeals — logos, ethos, pathos), and politeness strategies, some of which are culture-bound. The overall investigation manifests the diversity in language use which distinguishes Thai-style business requests from western-style ones. What Hinds (1990) calls a quasi-inductive style of writing or delayed introduction of purpose is a unique hedging strategy found exclusively in the TH letters. The NT requests tend to be more direct, often involving a ‘baldly on record’ strategy. In contrast in a similarly formal context, the TH request letters typically use more negative politeness in that they include more indirect, deferential and self-effacing strategies. According to the Aristotelian concept of persuasive rhetoric, the TH letters generally use a combination of logos, ethos and pathos whereas the NT letters tend to predominantly use a strong logos. These three rhetorical appeals can be regarded as persuasive strategies; the findings reveal some culture-specific differences in the persuasive strategies used in TH and NT letters of request.