In order to objectively evaluate the effectiveness, safety and usefulness of the new oral cephem cefpodoxime proxetil (CS-807, CPDX-PR) for the treatment of skin and soft tissue infections, a double-blind comparative study was undertaken using cefaclor (CCL) as the control drug. CPDX-PR and CCL were administered for 7 days at daily doses of 400 mg (divided into 2 portions) and 750 mg (divided into 3 portions), respectively. A total of 243 patients (118 in the CPDX-PR group and 125 in the CCL group) was treated in this study. The effectiveness, safety and usefulness were evaluated in 222 (106 in the CPDX-PR group and 116 in the CCL group), 234 (113 in the CPDX-PR group and 121 in the CCL group) and in 223 patients (107 in the CPDX-PR group and 116 in the CCL group), respectively. There were no differences in patients' backgrounds between the 2 groups, except for the presence or the absence of surgical treatments. The results we obtained are summarized below: 1. In the evaluation of clinical efficacy by the subcommittee, excellent, good, fair and poor efficacy were observed in 36, 43, 17 and 10 patients in the CPDX-PR group, respectively; the efficacy rate was, therefore, calculated to be 74.5%. As for the CCL group, respective results were observed in 50, 39, 17 and 10 patients, indicating an efficacy rate of 76.7%. There was no significant difference between the 2 groups. Improvement rates judged by physicians in charge were 80.2% in the CPDX-PR group and 88.8% in the CCL group. Moreover, no significant difference in diseases or severity were found between the 2 groups. 2. As for the bacteriological efficacy, the 2 groups showed high elimination rates, as 90.1% and 91.6% of the disease causing bacteria were eliminated in the CPDX-PR group and in the CCL group, respectively. Elimination rates in single infections with Staphylococcus aureus were determined to be 85.7% in the CPDX-PR group and 85.0% in the CCL group. 3. Although 6 patients in the CPDX-PR group and 2 patients in the CCL group developed side effects, which were mainly gastrointestinal symptoms, there was no significant difference in the incidence of side effects between the 2 groups. Abnormal laboratory values were found in 5 patients in the CPDX-PR group and 1 patient in the CCL group. 4. There was no significant difference in the usefulness between the 2 groups.(ABSTRACT TRUNCATED AT 400 WORDS)