This paper presents an analysis and a description of the most common prepositional errors in Spanish as a Foreign Language (SFL). Based on the methodology originally proposed by Corder (1967, 1971), we have analysed the texts produced by 18 learners of Spanish as a Foreign Language. These texts were grouped in a corpus that recompiled 48 abstracts. Then we have proceeded to the description of the prepositional errors identified. The article also presents the results of the analysis carried on this corpus. We could therefore observe a frequent use and a significant number of errors.