To investigate primary care physicians' knowledge of and attitudes toward care for chronic kidney disease patients. In Brazil, care for chronic kidney disease, a global public health problem, is provided by the Brazilian National Health System, which is organized around primary care. The study aimed to investigate the knowledge and attitudes of primary care physicians about the management of chronic kidney disease. This research is based on quantitative and qualitative data. The participants were 92 physicians from 81 primary care units located in eight cities of the São Paulo/Brazil health region, who answered a self-administered questionnaire. Only 59% and 58% of the physicians recognized smoking and obesity, respectively, as risk factors for chronic kidney disease. Health appointments and drug therapy predominated as disease prevention strategies and less than 30% mentioned multiprofessional care and health education groups. For early diagnosis, isolated serum creatinine was the most used test and 64.6% stated they classified the disease stages. Exclusive follow-up in primary care decreased from 79% in stage 1 to 19.5% in stage 3B and the patients' monitoring in the healthcare network varied from 8.7% in stage 1 to 70.6% in stages 4 and 5ND, suggesting early referrals and lack of referral at the necessary stages. Access to information on the referred patient was, predominantly, through the patient's report and 74% of the physicians did not have matrix support regarding chronic kidney disease. The study showed that the healthcare teams need to update their knowledge and procedures to be able to provide a comprehensive and efficient approach to treating chronic kidney disease in primary care.