Purpose: This study was aimed at (a) describing professional nursing practice environments embedded in nursing care units and (b) examining its relationships to nurses' task motivation. Method: Using the Nursing Work Index Revised (NWI-R) and the Work Preference Inventory (WPI), a descriptive study was conducted with a sample of 320 registered nurses on 26 nursing care units in one University hospital in Korea. Result: Mean scores were 12.9 on a 5-20 score range of an autonomous environment scale, 7.3 on a 3-12 score range of a collaborative environment, and 15.8 on a 7-28 score range of control over nursing practice. Nurses' age, educational level, job position, working period at the hospital and employment status were significantly related to the degree of a professional practice environment. The extent to which a professional practice environment accounted for task motivation was 19.5%. Conclusion: There is a certain degree of professionalism in the workplace environment that nurses perceived within the nursing care units. When nurses care for patients, the degree of task motivation depends on the work environment supporting the professional nursing practice.