Pneumocystis carinii pneumonia is one of the most common and severe infections in patients with human immunodeficiency virus (HIV) infection. Classically, the diagnosis of this condition is made with aggressive techniques such as fibrobronchoscopy (FBS) with bronchoalveolar lavage (BAL) or pulmonary biopsy. Sputum induction is a relatively recent technique which permits the diagnosis in a rapid, inexpensive way which is not aggressive for the patient. We have carried out 22 sputum inductions during a 4 month period. All patients had HIV infection and clinical, radiological and gasometric features consistent with P. carinii pneumonia. P. carinii cysts were found in the BAL of 6 patients and in 4 (66%) of the sputum samples induced from them. These still preliminary data support the need to generalize this procedure to achieve a greater experience in the different institutions, so as to achieve a higher yield of a technique which has clear advantages over previously used ones.