Although reports of serious infections in clinical trials for rheumatoid arthritis (RA) with tocilizumab, anti-interleukin6 (IL-6) receptor antibody, have been relatively few, there is still some concern about infections. We report here two cases of patients who developed severe pneumonia during tocilizumab treatment for RA. Both patients initially presented with only minimal clinical symptoms and modest elevations in serum C-reactive protein. Tocilizumab might suppress the early inflammatory symptoms of pneumonia.