This study investigated the use of politeness strategies in a corpus of English business letters written by Iranian non-native speakers in comparison with business letters written by English native speakers. The positive and negative politeness strategies proposed by Brown and Levinson’s (1978) theory were employed. A corpus of 46 business letters written by non-native employees of four companies and 46 letters written by native speakers who were in correspondence with these companies were analyzed to examine their use of politeness strategies. Th e results collected from the analysis of letters written by nonnative parties as senders were compared to those written by native speakers as receivers in response. Th e findings showed that although both parties used both types of politeness strategies in their letters, non-native participants employed both types (negative and positive politeness strategies) more than native speakers, especially positive politeness strategies, which were found to be used more frequently than negative ones. Additionally, the results demonstrated that social distance plays an important role in the employment of different strategies, particularly in choosing the type of salutation, which is an act requiring the positive politeness strategy to reduce face threatening act. Th us, more frequent use of positive politeness strategies by non-native speakers could be an effect of this factor.