It has been repeatedly shown that exposure to formaldehyde produces progressive loss of tissue epitopes. In the past few years, different physical methods-for example, techniques based on ultrasound (US), microwave (MW), and pressure cooker (PC) technology-have been developed for recovering masked antigens and allowing immunohistochemical (IHC) staining. Taking into account that many antigens were recovered using these retrieval methods after deparaffination of tissue sections, we wanted to test whether it is possible to recover muscular desmin, as an antigen model, before tissue embedding in paraffin (i.e., preembedding epitope retrieval [PRER]). For this purpose, the three physical retrieval methods already mentioned were employed and statistically compared, and a comparison with the conventional postembedding epitope retrieval (POER) techniques was also made. We have found that preembedding treatment with MW and PC methods was entirely inappropriate for the recovery of desmin in tissue blocks, whereas the US PRER was able to unmask desmin in most formalinfixed skeletal muscle pieces and the combination of US PRER and different POER methods allowed a greater amount of desmin to be unmasked. Additionally, no overheating of tissue blocks or detachment of tissue sections was observed; thus, this approach could be suitable to obtain enough material for hundreds of sections to work with as many unmasked epitopes as possible in a few seconds of sonication.