The Mongolian gerbil displays a pronounced social behaviour and is kept increasingly as an experimental animal. The objective of this study was to analyse social interactions and the reproduction of these rodents, which live in families in the steppe and semi-desert regions of Mongolia and Manchuria. Moreover, their welfare was evaluated based on established parameters and newly developed methods and recommendations are given for improved housing conditions. By using implanted transmitters in association with biotelemetry, heart rate, body temperature and activity indicated the physiological state and the ongoing changes during gravidity and lactation in a Mongolian gerbil with no apparent side effects. While parental animals coordinated their care behaviour when rearing the young, the circadian rhythm remained unaffected by social stimuli. The female sexual cycle, which is important for the male-female relationship, could unambiguously be determined via ethological and cytological parameters and the male influence on the stability of the cycle was evaluated. The proven daytime effect on the stress response (stronger response during the rest time) led to the recommendation to perform animal house routines during the activity time of the animals. The analysis of the body composition, an important phenotypic parameter for animal welfare and sociobiological studies, could be successfully carried out by using the newly established method of the total body electrical conductivity (TOBEC).