The research was undertaken with the intention of testing six null hypotheses regarding the retention of basic cardiopulmonary resuscitation (CPR) skills and knowledge of registered nurses The hypotheses were formulated from the broad aims of the research, which were to investigate conclusions reached by other researchers highlighting the speed with which retention of CPR skills and knowledge deteriorates, and to investigate the need for regular updating in CPR The research was quasi-experimental in nature The 19 nurses participating in the research were qualified staff undertaking the English National Board (ENB) 923 course in Professional Development, which included a refresher on basic CPR skills and included some discussion regarding advanced techniques The latest guidelines issued by the Resuscitation Council (1993) were used, which also aided in the design and use of the two research tools, namely an eight-point skills-testing observation tool and a 26-point knowledge-testing questionnaire While a 3-hour update in CPR skills revealed an initial improvement, the decrease in retention of skills 10 weeks later was significant (P=0 0000) The update in CPR knowledge also revealed an initial improvement but the decrease in retention of knowledge 10 weeks later was significant (P=0 0000) The findings of the research reflect similar results to previous research undertaken and discussed in the literature review, suggesting that retention of skills and knowledge quickly deteriorates if not used or updated regularly Therefore this research supports the importance of CPR refresher courses on a regular basis