AIM: To analyze the perception of nursing professionals of the Madrid Primary Health Care environment in which they practice, as well as its relationship with socio-demographic, work-related and professional factors. DESIGN: Cross-sectional, analytical, observational study. PARTICIPANTS AND CONTEXT: Questionnaire sent to a total of 475 nurses in Primary Health Care in Madrid (former Health Care Areas 6 and 9), in 2010. MAIN MEASUREMENTS: Perception of the practice environment using the Practice Environment Scale of the Nursing Work Index (PES-NWI) questionnaire, as well as; age; sex; years of professional experience; professional category; Health Care Area; employment status and education level. RESULTS: There was a response rate of 69.7% (331). The raw score for the PES-NWI was: 81.04 [95%CI: 79.18-82.91]. The factor with the highest score was "Support from Managers" (2.9 [95%CI: 2.8-3]) and the lowest "Workforce adequacy" (2.3 [95%CI: 2.2-2.4]). In the regression model (dependent variable: raw score in PES-NWI), adjusted by age, sex, employment status, professional category (coefficient B=6.586), and years worked at the centre (coefficient B=2.139, for a time of 0-2 years; coefficient B=7.482, for 3-10 years; coefficient B=7.867, for over 20 years) remained at p≤0.05. CONCLUSIONS: The support provided by nurse managers is the most highly valued factor in this practice environment, while workforce adequacy is perceived as the lowest. Nurses in posts of responsibility and those possessing a higher degree of training perceive their practice environment more favourably. Knowledge of the factors in the practice environment is a key element for health care organizations to optimize provision of care and to improve health care results.