This study examined the Slovak mutations of three outcome measures for routine practice i.e. the Clinical Outcomes in Routine Evaluation - Out-come Measure (CORE-OM), the Outcome Questionnaire - 45 (OQ - 45), the Outcome Rating Scale (ORS), and one control measure the Symptom Checklist 10 Revised (SCL-10R), with regard to their concordance or differences in outcome classification of pre-post change, when used by the same patients and when the criteria used for establishing recovery and improvement status are based on the same sample. Method: Non-clinical (252) and clinical (202) samples were used for the standardisation of all instruments. A portion of the clinical participants (N = 140) completed all measures at the end of their treatment. Results: The CORE-OM, and the SCL-10R indicated a higher number of recovered and improved clients. With regard to the pre-post differences as expressed in the effect size, the CORE-OM showed the highest pre-post difference (pre-post effect size .98), followed by the ORS (. 87), the SCL-10R (. 83) and finally with the OQ-45 (. 69). Conclusion: Even very similar instruments developed on the basis of similar theoretical conceptualisations and empirical findings may report different pre-post outcomes.