The design and attractive outfit of products and tools very often are cues which encourage somebody to buy them. Yet, the first impression and the succeeding working experience sometimes diverge considerably. Furthermore, stereotypical behavior and traditional habits as well as the lack of numbers and figures indicating the ergonomic quality and the utility values of a product or working tool are obstacles to the introduction of actually innovative items. The same is true for the handle of a mason's trowel, which has been developed some years ago but has not achieved general acceptance in bricklaying. Therefore, the objective of this study was to evaluate the ergonomically designed handle of a mason's trowel in comparison with two standard types, both with a round cross-section of the handle and either a straight neck or a swan's neck. All the tools were equipped with the same blade. Job-specific dynamic and static working elements were performed by 10 subjects in a laboratory. Under well-controlled conditions, physiological cost associated with mixing and throwing of mortar onto a vertical wall, translatory carrying and depositing of sand on a horizontal wall, rotatory scooping movements (supination and pronation of the forearm) with and without an external load of the trowel, and static holding of the tool in different working postures were measured. Electromyographic activity (EA) of the biceps brachii, pronator teres, flexor digitorum, and extensor carpi ulnaris was registered continuously and summed up during all of the test sessions lasting 30 or 45 s, each. All data were standardized by means of maximum EA resulting from preceding job-specific maximum voluntary contractions. Before and after the working sessions, which lasted about 4 h for each subject, the ergonomic quality of the handles had to be rated by means of a questionnaire with 9 items on a bipolar 4-step scale. In accordance with the hypothesis that the ergonomically designed handle should enable a specific relief of the strain in the grip musculature and the ulnar deviation muscles, significantly lower EA values were measured with this model during most of the test phases. But the effect was much less in scale than was expected from the subjective assessment before the tests. Also, subjective rating data after the working sessions differed clearly between the three handles mostly corresponding with the pretest assessment.