The purpose of this trial was to evaluate the effects of decoquinate at 2.5 mg/kg/day for 21 days to prevent an experimental cryptosporidiosis in kids. Twenty 1-day-old male kids (French Alpin), fed initially goat colostrum heated 1 h at 56 degrees C and fed twice daily with nonmedicated milk replacer, were assigned into 2 groups. Kids of both groups were orally inoculated with 10(6) Cryptosporidium parvum (D0 = inoculation day). Group A kids were kept as nonmedicated controls and group B kids were orally medicated with 2.5 mg/kg/day of decoquinate (Deccox L. Rhône Poulenc Animal Nutrition) for 21 days from D-3 to D17. The studied criteria were body weight gain, oocyst shedding and specific anti-C. parvum immune response. In group A, the inoculation was not followed by mortality; but only by diarrhea and high oocyst shedding. Decoquinate reduced the severity of cryptosporidiosis in group B kids. The treatment prevented episodes of diarrhea and weight gain decrease for the D0-D7 and D0-D14 disease periods but did not allow a better final weight gain. The oocyst shedding was decreased in number and in duration. This parasitic development has induced a specific anti-C. parvum immune response. This drug is well-tolerated by animals and may be recommended in the prevention of ruminant cryptosporidiosis, a disease which has very limited treatment options.