OYAK subsidiaries include ATAER established so as to have affiliation in the companies that engage in activities in various sectors, OYAK Güvenlik providing physical and electronic security services, OYAK İnşaat developing building projects and construction works, OYAK Pazarlama providing hygiene, technical, tourism - organization and technological services, OSİAT which is a business administration and MicroMedicine engaging in activities in the field of medical technologies, OYAK Sermaye Yatırımları established so as to evaluation of investment opportunities.