We present the results of a protocol of empiric monotherapy of continuous ambulatory peritoneal dialysis (CAPD)-related peritonitis with ciprofloxacin (CPX), with a special emphasis on the evolution of our results after seven years of continued use of this drug. One hundred and fifteen episodes of bacterial peritonitis were treated with CPX between 1988 and 1992 (group A), and 115 episodes were treated between 1993 and 1995 (group B). The etiologic spectrum of peritonitis was similar in both groups, except for a higher incidence of polymicrobial infections in group B. The clinical success rate decreased from 86.5% in group A to 75% in group B (p < 0.05). This was partly due to the high failure rate of CPX against polymicrobial peritonitis, but the success rate also tended to decrease for gram-positive and, especially, gram-negative bacteria. However, in vitro sensitivity to CPX decreased only for coagulase-negative staphylococci, remaining stable for Staphylococcus aureus and gram-negative bacteria. CPX is still a valid alternative for the treatment of CAPD-related peritonitis in our unit. However, bacterial sensitivity must be closely monitored, especially in the case of coagulase-negative staphylococci. A different therapeutic approach may be indicated if polymicrobial peritonitis is suspected.