Cryptosporidiosis in patients with AIDS often leads to a severe wasting illness that is difficult to treat. Recent reports suggest that paromomycin may be useful in the treatment of intestinal cryptosporidiosis. We reviewed our experience using paromomycin for the treatment of cryptosporidiosis in seven patients with AIDS. All patients received paromomycin (500 mg orally every 6 hours) for an average of 11.7 days. The mean follow-up period was 3.2 months. All patients had an initial response to paromomycin that was characterized by a decrease in frequency of diarrheal episodes, stabilization of body weight, and/or eradication of cryptosporidia from the stool. The mean number of diarrheal episodes decreased from 10.9 to 1.7 daily. Stabilization or increase in body weight was noted for five of seven patients, and eradication of oocysts was documented for three patients. Relapses or recurrences were noted for three patients. Treatment with paromomycin was well tolerated by all patients with the exception of two, who experienced nausea and abdominal discomfort. Thus, paromomycin appears to be a promising agent for treatment of acute cryptosporidiosis.