Introduction: Foreign research shows that gambling disorder and alcohol use disorder are significant public health problems with continuous growth in recent years, and same tendency has been noted in Croatia. Patients with behavioural addictions, such as gambling addiction, resemble alcohol addicts in that they also manifest cravings, compulsive behaviour, physiological and psychological symptoms of abstinence, loss of control, development of tolerance and susceptibility to psychotropic effects. Gambling-related problems first referred to as pathological gambling and classified as an impulse control disorder in the Diagnostic and Statistical Manual of Mental Disorders (DSM) have since been renamed gambling disorder and assigned to addiction disorders. This puts gambling-related problems in the same category as addictions to psychoactive substances. This reclassification reflects similarities between gambling addiction and substance addiction in terms of clinical course, genetic risk factors, therapeutic interventions, as well as neurocognitive and neurobiological changes. After reclassification in DSM-5, classification in ICD-11 is just to be expected, but there is also the lack of structured research aiming to compare substance and non-substance use patients, such as alcohol addicts and gambling addicts. Aims of the research: The aims of this research are to determine (1) psychosocial functioning characteristics of persons treated for alcohol addiction and persons treated for gambling addiction, (2) potential differences between these two groups and (3) differences of psychosocial functioning with regard to problem intensity. Patients and methods: The sample consists of N=194 alcohol addicts (n=140; 72.16%, Mage=53.09; SDage=11.09) and gambling addicts (n=54; 27.84%; Mage=24.69; SDage=7.72), members of clubs for treated alcoholics and members of clubs for treated gambling addicts in Zagreb area. In order to conduct this research, a wide battery of instruments was used: (1) Questionnaire about general and socio-demographic data, (2) Questions related to general health status, (3) Questionnaire of gambling activities, (4) Question about gambling on web and on mobile applications, (5) Questions related to therapy and characteristics of alcohol consumption and gambling, (6) Questions about quality of social interactions, (7) South Oaks Gambling Screen – SOGS, (8) DSM-5 scale for alcohol use disorder – self evaluation version, (9) DSM-5 scale for gambling disorder – self evaluation version, (10) Alcohol Use Disorder Identification Tool – AUDIT, (11) Coping Inventory Stress Situations – CISS, (12) Barratt impulsiveness Scale, BIS-11, and (13) Depression Anxiety Stress Scale, DASS-21. In order to achieve aforementioned aims, in this cross-sectional research, beside descriptive statistics (means, standard deviation, frequencies, Hi-square test), nonparametric method for comparing differences, precisely Mann-Whitney U-test, with testing size effect, was used. Results: The results have shown that the most significant difference was related to basic addictive behaviour, whereas in psychosocial functioning these two subsamples are less different. In relation to addictive behaviour, we found that members of KLOK currently drink more than addicts in KLA, whilst alcohol addicts had much higher results in all other aspects of alcohol addiction. Gambling addicts gamble more frequently, especially games with high addictive potential (effect size for sports betting, slot machines and roulette was large, ranging from .62<r<.66) which is additional contribution to the explanation that lotto has much lower addictive potential than other gambling activities, especially sports betting, slot machines and roulette. Within the context of psychological functioning and personality traits, gambling addicts have higher results in certain dimensions of impulsivity such as motor (MW-U=3087; p<.050; r=.14) and self-control (MW-U=2682; p<.010; r=.22), whereas task-oriented coping (MW-U=3013; p<.050; r=.15) and avoidance-oriented coping (MW-U=2716; p<.010; r=.21), as well as lower satisfaction in relationships with friends are more characteristic for alcohol addicts. Effect size of the aforementioned differences is medium in impulsivity dimension described as self-control which is more prominent in gambling addicts, and in avoidance-oriented coping which is more present in alcohol addicts. Small effect size is registered in motor impulsivity, task-oriented coping and in satisfaction in relationships with friends. When questioning differences of psychosocial functioning related to addiction problem intensity, the results show that cognitive instability (MW-U=2661; p<.050; r=.15) and stress related symptoms of psychopathology (MW-U=2617; p<.050; r=.15) are moderately prominent in addicts with more severe intensity of addiction with small effect size.