This study was aimed at analyzing the monthly cost of the use of specialized equipment by ostomy patients. It is a retrospective study carried out at two Outpatient Health Centers in São Paulo. The data were collected in 635 records of adult ostomy patients assisted in June of 2005. For the costs, the data were obtained in electronic databases and official publications from the State of São Paulo Health Secretary, and the results were submitted to the Kolmogorov-Smirnov, Mann-Whitney, Kruskal-Wallis, Bonferroni and Spearman tests. Most of the individuals were female (51%), aged > or = 60 years, with temporary colostomy (64.5%). The average monthly cost was US$ 51.0 per patient, higher for cancer urostomy patients with permanent stomas, with neoplasia in the urinary tract and assisted by the service with a therapist nurse. Statistically significant correlation between the monthly cost and the time with stoma was found. This study has contributed for the assessment of the cost of ostomy patients in the State of São Paulo.