Even when utilizing ergonomically designed flat keyboards, longer lasting periods of work with a word processor or typewriter can cause physical complaints. In this context, a specially developed armrest is said to enable more comfortable working and to prevent physical complaints. Therefore, the objective of this study was to assess the effects of this armrest via an experimental investigation. Ten male subjects (Ss) participated in tests at an already ergonomically optimized VDU workplace where continuous input of the same text was demanded in sections with and without the armrest. Before and after the tests, the subjects had to subjectively rate important criteria of the armrest. During the tests, muscular strain associated with working was measured continuously via electromyographic activities (EA) of 5 muscle groups. These data – as indicators of “physiological cost” – were essentially lower when using the armrest. On the contrary, by relating EA values without the armrest to those with the working aid, it could be shown that working without the armrest is far more strenuous than working with it. Subjective assessments after the tests, as opposed to prior to the tests, corresponded well with the objectively measured physiological data.