Biological drugs are therapies designed to target a specific molecule of the immune system that have been linked with the development of autoimmune diseases. Areas covered: The BIOGEAS Registry currently collects information about nearly 13,000 reported cases of autoimmune diseases developed in patients exposed to biologics, including more than 50 different systemic and organ-specific autoimmune disorders, of which psoriasis (n=6375), inflammatory bowel disease (n=845), demyelinating CNS disease (n=803), interstitial lung disease (n=519) and lupus (n=369) were the most frequently reported. The main biologics involved were anti-TNF agents in 9133 cases (adalimumab in 4154, infliximab in 3078 and etanercept in 1681), immune checkpoint inhibitors in 913 (ipilimumab in 524 and nivolumab in 225), B-cell targeted therapies in 741 (rituximab in 678), and growth factor inhibitors in 549 cases (bevacizumab in 544). Even though targeting a particular immune molecule may be associated with an excellent clinical response in most patients, an unexpected autoimmune disease may arise in around 8 out of 10,000 exposed patients. Expert opinion: Following the increased use of biologics, the number and diversity of induced autoimmune diseases is increasing exponentially. Management of these disorders will be an increasing clinical challenge in the daily practice in the next years.