Biologic use is a major advance in the treatment of several autoimmune conditions, including rheumatoid arthritis. In this review, we summarize key studies of serious/hospitalized infections in rheumatoid arthritis (RA). RA is a risk factor for infections. High RA disease activity is associated with higher risk of serious infection. The risk of serious infections with tumor necrosis factor inhibitor (TNFi) biologics is increased in the first 6 months of initiating therapy, and this risk was higher compared to the use of traditional disease-modifying anti-rheumatic drugs (DMARDs). Emerging data also suggest that biologics may differ from each other regarding the risk of serious or hospitalized infections. Past history of serious infections, glucocorticoid dose, and older age were other important predictors of risk of serious infections in patients treated with biologics.