BMC Public Health 2007, 7:27 http://www.biomedcentral.com/1471-2458/7/27 "Such conditions give a freedom of action that is benefi- cial to health" [25]. Cigarette smoking has been shown to have a strong effect on health in various countries of the former Soviet Bloc in terms of mortality and morbidity [26-28]. However, smoking, like other unhealthy lifestyles, may be caused by the stressful psychological environment and social cir- cumstances in these countries [19,29,30]. Acculturation – a complex social, cultural, and psycholog- ical process of adapting to a different society [31], is another determinant of mental health among immigrants from the FSU [10,32,33] and probably among immigrants from other countries of the former Soviet Bloc as well. An often used proxy of acculturation in quantitative studies is the mastery of the language of the host country. Greater mastery of the language has also been associated with bet- ter mental health in FSU immigrants [33]. The length of time since immigration has often been referred to as a health determinant and an indirect indica- tor of acculturation. Ritsner & Ponizovsky have shown that the acculturation of immigrants, and particularly the path of psychological distress connected with the process of acculturation, is not linear or U-shaped, but occurs in several phases [34]. Therefore, it is not necessarily true that the longer immigrants have spent in the host country, the better their acculturation and health will be. However, years spent in the host country and the year of immi- gration may also indirectly represent the reason for migra- tion, particularly for immigrants from the former Soviet Bloc to Sweden. While the late 1990s and the beginning of the new millennium brought many economic, labor and family reunion immigrants to Sweden from the coun- tries of the former Soviet Bloc, the previous decades were generally characterized by the wave-immigration of asy- lum-seekers and political refugees escaping from the per- secutions in the Soviet Bloc. The premigration experiences of life under comunist rule, defined by central planning, coercion, terror and communist nationalism [35] with the absence of basic human rights or freedoms and with one political party's domination in all aspects of economic and social life [36] could have affected immigrants' health. However, the studies do not agree on whether there is a relationship between health status and the com- munist regime per se (for a review, see [37]). However, just how the change from a communistic regime to democracy as a result of emigration negatively affects the mental health of Soviet immigrants has been the subject of debate [38]. Years spent in the host country also constitute the period of time when immigrants have been exposed to the post-migration factors in the host society. Migration to a country with different patterns of health and health behaviors, with greater economic satisfaction among its inhabitants and a different civil society might benefit the immigrant's health in time. On the other hand, such stres- sors of immigration as novelty, not feeling at home in the host country, sense of loss, and discrimination [10] in the host country might affect health negatively. There are various possible pathways of causal influence between these, as well as other factors not mentioned here, and the mental health of immigrants from the former Soviet Bloc. The discussion of each one of them deserves consideration in its own right. Unfortunately, this is not possible in a short article. We therefore limited the scope of this study to the health determinants that have been particularly known to influence the health of persons born in these countries. Our intention in this study was to find out whether these determinants could explain the poorer mental health of immigrants from the former Soviet Bloc often reported in other studies [9,10,38-43]. Thus, the purposes of this study were: (1) to study whether the self-reported mental health (measured here as self-reported psychiatric illness and psychoso- matic complaints) was poorer among persons born in the countries of the former Soviet Bloc currently living in Swe- den than among Swedish-born persons and (2) to investi- gate whether the demographic, socioeconomic, and immigration-related characteristics of respondents could explain this. Methods Setting and sample This study was based on eight pooled, cross-sectional ran- dom samples of permanent Swedish residents (including immigrants with permanent residence permits or Swedish citizenship). The samples consisted of men and women aged 25 to 84, of whom 385 were immigrants from Poland (n = 161), Eastern Europe (n = 164), and the FSU (n = 60) who arrived in Sweden after 1944. The informa- tion was collected by trained interviewers in face-to-face interviews as part of the Swedish Annual Level of Living Survey (SALLS) between 1994 and 2001. The reliability of the survey questions was tested in other contexts in Swedish [44] and Latin American [45] sub- samples and was found to be high. Moreover, the external validity of the self-reported severe or very severe long- standing illness was high. An overreporting frequency of 10% and underreporting of 20% was found [45,46]. Although ideally it would have been desirable to test the reliability of the questions in the immigrants from the former Soviet Bloc as well, this was not possible because the current study was undertaken 5 to 12 years after the original surveys (1994 to 2001) were made. Page 4 of 12 (page number not for citation purposes)