The fundamental goal of this study was to measure the levels and causes of stress of employees in an organisation undergoing immense change, including a transaction whereby the full administrative and managed healthcare operations are sold to a prominent insurance company (acquisition). This change represents an acquisition of the intellectual capital and systems of a mutual open medical scheme by a major insurance company with a well established brand equity and profile in the South African insurance market. The importance of the study is imperative as it forms an integral part of the management of change programmes. The goal is to execute a paradigm shift in leaving behind old comfort zones and moving towards a competitive workforce in a highly competitive environment with an outcomes based approach to business. The identification of the most important levels and causes of work stress will enable the organization to address factual situations and to build these strategies into its change programmes, whilst not relying on generic, non-focused initiatives with marginal success outcomes. Some organisations are more stressful than others and in order to manage stress and embark on effective strategies to cope with stress, the unique disposition of the organisation and its employees needed to be identified. The data was collected electronically via the organisation’s Intranet by means of the Experience of Work and Life Circumstances Questionnaire (WLQ), compiled by Van Zyl and Van der Walt of the Human Sciences Research Council in 1991. The questionnaire was developed to determine the levels and causes of stress of employees. The WLQ endeavours to establish whether employees experience normal, high or very high levels of stress and also identify those factors which cause these levels of stress. The questionnaire consists of three different parts namely, a demographic questionnaire, experience of work which determine the levels of stress and finally, circumstances and expectations which analyses the causes of stress. It was clear from the study that organisational change, such as is experienced by the employees of this organisation, does lead to increased and higher stress levels. It was further demonstrated from the results that uncertainty and lack of control over their own destiny and immediate circumstances, contributed to an increase in the levels of stress. Copyright 2009, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: V an Zyl, P 2009, The measurements of levels and causes of work stress of employees in a competitive open medical scheme in the privater sector, MCom dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-03152012-170001 / > C12/4/69/gm / Dissertation (MCom)--University of Pretoria, 2009. / Human Resource Management / unrestricted