Background: Analyzes of negative consequences of workaholism are ambiguous, and various studies have been conducted with different measurement tools. Thus, the objective of the current research was to find the answer to the question about relationships between workaholism measured with varied tools and mental health, stress experienced in life and at work, negative affect, and work–family conflicts. Material and Methods: The study was conducted in a group of 178 subjects (71 men, 107 women, aged 23–66), with a minimum work experience of 4 years. To measure workaholism 4 different research tools, based on different conceptualization of this construct, were used: Workaholism Battery (Work-Bat) by Spence and Robbins, Work Addiction Risk Test (WART) by Robinson, Scale of Workaholism as Behavioral Tendencies (SWBT) by Mudrack and Naughton, and The Scale of Being Absorbed by Work (SZAP) by Golińska. To measure possible consequences of workaholism the following tools were employed: General Health Questionnaire-28 (GHQ-28) by Goldberg, Scale of Work–Family/Family–Work Conflict (WFC/FWC) by Netemeyer et al., Perceived Stress Scale (PSS) by Cohen et al., Brief Scale of Vocational Stress (BSVS) by Stanton et al. and Mood Scale by Wojciszke and Baryła. Results: The strongest relationships between workaholism and its negative consequences for the functioning of the unit can be observed using 2 diagnostic methods, respectively: WART and SZAP adapted by Golińska. Other diagnostic tools (Work-Bat and SWBT) have insignificant relationships with possible negative consequences of workaholism. Conclusions: The applied method of measuring workaholism seems to be of great importance in predicting possible consequences-different conceptualizations of phenomena leading to different results, which is important for researchers and practitioners involved in the issue of workaholism. There is a need for further work on the conceptualization and operationalization of the workaholism phenomenon. Med Pr 2016;67(4):467–476