This article presents the results of author’s research conducted within the scope of the self¬assessment of knowledge workers’ professional threats resulting from improper equipment or technical organisation of a workplace. The article includes the schedule of variables connected with the technical organisation of the workplace, i.e. lighting and temperature. Afterwards the author examined whether the working environment of respondents affects the possibility of full concentration on the fulfilment of professional duties. The author also examined the possibility of occurrence of sight problems and disorders of musculoskeletal system, both perceived as threats resulting from improper organisation of a workplace from the ergonomic point of view. Factors presented above were analysed depending on a work character performed by knowledge workers.