Despite the clinical significance of inpatient group treatments, there is a lack of evidence related to its effectiveness. Following several years of narrative reviews, Kösters et al. (2006) have published a first meta-analysis of inpatient groups that provides the basis for this article. To evaluate the effectiveness of inpatient groups, those studies from German-speaking countries which have been part of the meta-analysis were considered and completed with some recent publications. Within the meta-analysis, only pre-post effect sizes were calculated because of a lack of controlled studies. To determine the comparability of the single studies, a statistical index describing the studies' heterogeneity was computed (I ²-statistics). As in the meta-analysis of 2006, the study showed a mean effect size of d = 0.58 for a total of 64 pre-post-comparisons and a relatively high heterogeneity of the studies. A differentiation of studies dealing with anxiety disorders lead to a reduction of heterogeneity and, simultaneously, revealed significant differences between subgroups. Other differences between diagnostics subgroups or depending on setting characteristics could not be determined. Methodological details of the meta-analysis are discussed in addition to the fact that inpatient group psychotherapy - despite some promising results - seems to be far away from the attribute of an "evidence based treatment", at least according to its current standards.