The invention relates to a method for the on-line testing of pipeline-type devices comprising a succession of stages (121, 122, 123) separated by buffers (111, 112, 113, 114, 115), each buffer (111, 112, 113, 114, 115) being linked to an idle signal, or valid = not idle, and/or at least one status bit. The invention is characterised in that it combines at least the following steps: a) detecting the values of the idle signal and/or the corresponding status bits representing the non-use of a cycle or a sudden interruption to the operation flow in a pipeline, and indicating that an operation (O3) executed by a stage of the pipeline, known as a valid operation, is monitored by a non-used cycle; b) maintaining the status of the buffer (111) in order to allow the re-execution of the valid operation (O3) during the non-used cycle indicated by the idle signal; c) during the non-used cycle, re-executing the valid operation (O3) in order to obtain at least a first version (O'3) and a second version (O"3) of the valid operation (O3); d) at the pipeline output, recording the results corresponding to the first version (O'3) of said replicated or re-executed operation (O3) in order to compare same to the results of the second version (O"3) of the same replicated or re-executed operation (O3); and e) comparing the results obtained at the pipeline output, corresponding to the first version (O'3) and to the second version (O"3) and, in the event of a difference, indicating the presence of an error.