There has been a growing trend towards a 24/7 society, with many services available at all hours, seven days a week. This can lead to changes in terms of quality of life. The aim of this study is to examine the effects of different patterns of shift work (length of shifts and speed of rotation) on the social and family life, mental health and psychological well-being of shift workers. The sample consisted of 104 participants, i.e. 65 men (62.5%) and 39 women (37.5%) with an average age of 38.58 years (SD=11.58), ranging from 23 to 64 years old. In order to collect relevant data, the following scales were used: Scale of Interference of Working Time with Social and Family Life – a scale adapted for the needs of this research, composed of part of the particles from the SSI (Standard Shiftwork Index; Barton et al., 1995) and particles from the scale NOR 1-9 (Scale of Negative Effects of Working Time Organization; Šimunić, 2008), Scale of Interference of Working Time with the Performance of Formal Tasks – a scale adapted for the needs of this research, composed of a part of the particle from the SSI (Standard Shiftwork Index; Barton et al., 1995) ), SF-36 Scale; subscales Mental Health and Vitality (Ware et al., 1992; according to Maslić-Seršić and Vuletić, 2006), Job Satisfaction, Work Time Satisfaction, and a short Sociodemographic Data Questionnaire compiled for the purposes of this research. It was found that there is no difference in the interference of working hours with family and social life and the performance of formal tasks, with regard to the length of the working day. However, a significant, albeit weak, effect (դ 2=0.05) of the duration of the working day within a single shift on the estimated mental health of the participants was found. The direction of the differences points to more negative effects of 12-hour working hours compared to eight-hour working hours. Namely, participants who work 12 hours a day rate their mental health worse than participants whose working day lasts eight hours, yet they are significantly (դ 2=0.08) more satisfied with their working hours than participants whose working day lasts eight hours. A significant and large effect of shift rotation speed on all investigated variables was also determined. Speaking about the interference of working time with social and family life and the performance of formal jobs, all groups of shift workers who work in shifts at different speeds differ. Working hours interfere the least with workers whose shifts rotate every six days, and the most with shift workers whose shifts rotate every three days. Participants' rated mental health and vitality did not differ between the two-day rotating group and the three-day rotating group but was significantly worse in both of those groups than in the six-day rotating group. A significant and relatively strong effect of shift rotation on job satisfaction and working time was found, whereby the workers with the slowest shift rotation (every six days) were the most satisfied with their work, and on the contrary, the workers with the fastest shift rotation (every two days) were the most satisfied with the working time.