Previous researches have shown that any organization will be more competitive to achieve its mission and vision when the employees are practicing organizational citizenship behaviour (OCB) at the workplace. This OCB is also known as behaviour outside of an employee's job description that ultimately improves job performance in an organization; however, previous researches have shown that OCB is highly influenced by the organization culture. Interestingly, little is known which organization culture is affecting OCB among employees especially those that dressed in uniform such as the police officers. Hence, the aim of this research was to determine sub-dimensions of organizational culture affecting the practice of OCB among the Royal Malaysia Police (PDRM) in Selangor. Data were collected using a questionnaire through simple random sampling method, and results were analysed using Pearson correlation and Multiple Linear Regression among 571 Enforcement Personnel from six-branches of Police Headquarters Department in Selangor. Findings showed that organization culture explained 14.9% variance in OCB among respondents; however, only organizational integration and goals clarity were significant predictors influencing OCB although other components of organizational culture had significant relationship with OCB. Findings have implication for the PDRM to focus on nurturing organizational integration and goals clarity in order to stimulate OCB among their employees.