Background: The diagnosis of acanthamoeba keratitis has increased since 1985 due to the massive use of contact lenses and a better knowledge of the disease by ophthalmologists. The use of biassociated therapy has resulted in a better prognosis and lower complication rate. Aim: To report patients with acanthamoeba keratitis treated with the association of propamidine (Brolene(r)) and polyhexamethylbiguanide (PHMB) 0.02%. Patients and methods: Retrospective analysis of 27 patients (31 eyes) with acanthamoeba keratitis (bilateral in four cases), diagnosed by culture, biopsy or characteristic clinical features. Results: Ninety six percent of patients used rigid contact lenses. Acanthamoeba cultures were positive in 71% of cases. The delay in the diagnosis was between 1 and 5 months. Early treatment was possible in 29% of patients. Infection was erradicated in all cases with the biassociated therapy. A tectonic keratoplasty to treat a trophic perforation was done in eight eyes. No patient required therapeutic keratoplasty to resolve the infection. Visual acuity at the end of follow up was better than 20/40 in nine patients and in eight it was in the range of count fingers or less. Conclusions: In patients with the clinical picture of acanthamoeba keratitis, early or late antiamoebic treatment is warranted even in the absence of positive cultures. The visual results of the treatment are highly dependent on the precocity of treatment. Prevention is imperative and is based on a strict contact lens hygiene (Rev Méd Chile 2002; 130: 396-401)