Objective: To evaluate the risk of infections and malignancy in a group of patients with inflammatory rheumatic diseases treated with anti-TNF therapy. Methods: The study involved 79 adult patients with rheumatoid arthritis (RA) and ankylosing spondylitis, psoriatic arthritis or undifferentiated spondyloarthropathy (spondyloarthopathy (SpA)); receiving anti-TNF therapy at the department of Rheumatology and Rehabilitation, Clinical Hospital Center Zagreb. The duration of therapy was a minimum of 1 month, with the mean duration of 32,024,0 months. The infections recorded were infections that appeared during treatment or soon after the treatment was stopped. ----- Results: During the course of therapy 17 patients (21,5%) experienced an infection, with the total number of 21 infections. This resulted in an overall incidence rate (IR) of 9,9/100 patient-years. Of the patients with RA 76,5% developed an infection, which was significantly higher than for patients with SpA (p<0,001). The IR/100 patient-years for all infections in RA patients was 23,7 compared to 2,8 in patients with SpA. Female gender was associated with a significantly higher infection rate (70,6%, p=0,005). There were 8 infections that were considered serious, yielding an IR of 3,8/100 patient-years. There was only one malignancy case in our study. ----- Conclusion: Every fifth patient developed an infection during the course of anti-TNF therapy, and more than one third of all infections were serious. RA and female gender was associated with a significantly increased number of infections.