Clinical evaluation of cefotiam (panspolin), a new cephem antibiotics, was performed in the infectious disease associated with hematological disorders and in the respiratory system. In hematological dis orders, 40% of good and 25% of fair results were obtained in clinical effects. In respiratory infections, however, 92% of good results were obtained. Opportunistic infection due to Gram-negative bacilli are often experienced in patients with leukemia. Since cefotiam has sufficient bacteriocidal effects in broad spectrum, it would be a good therapeutic agent against infectious diseases associated with hematological disorders.