Integrating the Nurse Practitioner (NP) role into clinical practice settings is new in British Columbia (BC), Canada. Encounter codes are unique numeric codes assigned to specific types of patient care services performed by NPs. In this study we apply knowledge discovery techniques to analyze the encounter codes extracted from the BC Ministry of Health database to understand the most common practice activities carried out by NPs and what diseases patients sought care for from NPs. The analysis produced important information about NPs' practice patterns. This work leads to a better understanding of NP practice patterns in BC.