Adequate dietary phosphorus intake and the use of phosphorus binders are the main tools for treating hyperphosphatemia. Thus, its success depends essentially on the patient's ability to understand and adhere to the dietary plan and the use of phosphate binders.To evaluate hyperphosphatemic patients adherence and knowledge about phosphate control treatment.This is a cross-sectional study. One hundred and twelve patients on hemodialysis (60 males; age = 49.3 ± 13.3 years), from five dialysis centers with mean serum phosphorus > 5.5 mg/dL between July and December of 2008 (mean = 6.57 ± 0.73 mg/dL) were included. A questionnaire with questions about the consequences of hyperphosphataemia, foods high in phosphorus, appropriate use of phosphate binders and patient's opinion about reasons for treatment failure was administered. Laboratory parameters assessed were serum urea, calcium, phosphorus and parathormony (PTH), and dialysis adequacy by means of urea Kt/V.The average score of questionnaire was 78.5%. Regarding the reasons for the failure of the treatment of hyperphosphataemia, 87% indicated the response "because I eat more phosphorus than I should" and / or "because I do not take the phosphate binder as I should". Among those who said they did not use phosphate binder correctly, most (62%) justified to forget as the reason. The serum phosphorus correlated directly with serum urea (R = 0.33, p < 0.01) and inversely with Kt/V (R = -0.20, p < 0.05). There was no correlation between the phosphorus, the education level and the scores on questionnaire.Patients showed a good level of knowledge about the hyperphosphatemia treatment, but the vast majority were noncompliant to that. Strategies to improve compliance are necessary to decrease the incidence of hyperphosphatemia in hemodialysis patients.