The clinical efficacy, antibacterial activity and adverse effects of ciprofloxacin (CPLX) and ofloxacin (OFLX) produced in our country were compared in five clinical hospital in Beijing and Guangzhou in 1992. Two groups, each consisting of 100 cases, were treated with CPLX and OFLX respectively. The total cure rate was 79% and effective rate 94% after one course of treatment. There was no difference between the two groups (P > 0.05). The positive rate of presence of pathogens was 95% in both groups, but the rate of transformation from positive to negative after one course of treatment was 95.8% (OFLX) and 87.4% (CPLX) respectively. The difference between the two groups was significant (P < 0.05). 99 and 96 strains of bacteria were detected in the CPLX and OFLX group respectively; the elimination rate was 87.9% and 95.8% (P < 0.05). Incidence of adverse effects was 12% (OFLX) and 21% (CPLX) respectively. In a word, both drugs are effective in treating bacterial infections of digestive system, urinary system and respiratory tract. They are safe and reliable. OFLX is better than CPLX in bacteria elimination and incidence of adverse effects.