Colorectal cancer has been growing up last ten years in Chile, with 3.6 deaths per day. This has been the main cause of ostomies. The ostomy care is delivered by generalist nurses without specialized education which would difficult a holistic approach. Aims: develop a tool to measure the patients` perceptions about ostomy care delivered by Chilean nurses. Methods: After a literature review, the instrument was developed based on concepts established by Jean Watson Nursing Theory, related to transpersonal human caring. This considers the care as a moral subject which involves instrumental and expressive aspects towards a helping relationship. Electing the nursing theory, another generic instrument was found - The Caring Behaviour Assessement Tool (CBA) - developed by Cronin and Harrison and based on Jean Watson Theory. This instrument also focuses on a transpersonal aspect and involves the feelings and emotions aspects of caring, helping relationship, spiritual and phenomenological mechanisms among others. The caring factors from Watson Theory were related to five areas: human aspects of care, helping and confidence, teaching-learning, attention to human needs and psychological and spiritual support. The tool and Likert scale type were analyzed by committee composed of three ostomy care experts. The content validity was obtained with 80% agreement among judges. Results: The achromous PECCO Tool - PERCEPCCI"N DE COMPORTAMIENTO DE CUIDADO AL OSTOMIZADO - includes 42 items to assess nursing care behaviors distributed among the five areas of care. It is indicated for people above 15 years old and should be applied alter discharge. Conclusion: PECCO is a valid tool to asses nursing care behaviors delivered to ostomy patient in the pre and post surgical period. New reliability and validation measures are proposed to improve the tool.