To evaluate the effectiveness of involving primary care nurses in comprehensive care of patients with hypertension and diabetes mellitus type II (DM2). A quasi-experimental, before-and-after study was conducted, without a control group, in eight family-practice clinics. Trained nurses offered comprehensive care in conjunction with a team made up of a family doctor, a nutritionist, a social worker, and a dentist. The intervention lasted seven months and its outcome variables were changes in body mass index, fasting blood glucose, blood pressure, self-perceived health status, treatment compliance, and emergency services requests. Any change was determined by comparing the baseline to the final measurement through interviews and recording the variables of interest in a spreadsheet. In all, 1 131 patients completed the follow-up, of which 44.9% were diagnosed with hypertension, 27% with DM2, and 28.1% with both conditions. The proportion of patients seen by the coordinated health teams increased; there was a rise in cases of normal weight and overweight; a decrease in the proportion of obese (P < 0.05); and an increase in hypertensives with high blood pressure (< 130/ 80mmHg) (P < 0.05). There was no change in the proportion of diabetics with high blood glucose (< 140 mg/dl); 18.2% reported improved self-perceived health status (P < 0.05); there was improved treatment compliance (P < 0.05); and a decrease in requests for emergency services at the clinics (-4.5%) and at the hospitals (-6.8%) (P < 0.05). Comprehensive care for chronically ill patients through the involvement of nurses contributes to improved health outcomes in primary care.