Objectives: Analyse the correlation between changes in medical institutions' safety needle replacement rate and needlestick injury rate five years after the implementation of Article 56 of Taiwan's Medical Care Act. Methods: Using secondary data analysis, this study obtained needle usage data from the National Health Insurance Administration, Ministry of Health and Welfare during 2011-2016. Over the same period, needlestick injury incident data meeting inclusion criteria were sourced from the Chinese version of the Exposure Prevention Information Network database for analysis; the criteria are those data from hospital level institutions, those institutions which have reported data since 2011 and those institutions which persistently reported data during 2011-2016. With data from 36 institutions, it went further to estimate the needlestick injury rate among healthcare workers. Results: Five years after legislation was passed requiring hospitals to replace safety needles, the replacement rate for peripheral venous catheters reached 93.7%, whereas those for hollow needles and insulin injection needles were only 23.7% and 31.0%. Annual estimation of needlestick injury rates for various needle types in Taiwan indicated that needlestick rates for all needles and peripheral venous catheters have been declining but those rates for hollow needles and insulin injection needles are fluctuating. Correlation analysis revealed that higher safety needle replacement rates correspond to lower needlestick injury rates; notably, the peripheral venous catheter exhibited a significant negative correlation (r=-0.99, p＜.001). Conclusions: Although the Medical Care Act requires medical institutions to replace a full range of safety needles within five years of the implementation and the use of safety needles has indeed increased, their use in some categories remains limited. Better replacement rate of safety device was related to lowered injuries. Factors for incomplete implementation should be investigated in the future to facilitate further policy implementation and review.