In this paper, we reported some experiments conducted by our members in the SIG team at the IRIT laboratory in the University of Toulouse within the context of the medical information retrieval (IR) task. As in our previous participation in ImageCLEF, in 2011, our research focuses on the case-based retrieval task. We compared the performance of different state-of-the-art term weighting models for retrieving patient cases that might best suit the clinical information need. Furthermore, we also combined term scores obtained by two state-of-the-art weighting models using a particular data fusion technique. Finally, a state-of-the-art query expansion (QE) technique is used for improving biomedical IR performance. Key words: Biomedical information retrieval, Term weighting models, Query expansion, Model fusion