This study examined the effect of firm size on cash levels among listed healthcare firms in Nigeria. This study adopts an ex-post facto research design. The population and sample size were made up of 7 listed healthcare firms and 5 listed healthcare firms, respectively. Secondary data for the study were sourced from firms’ annual reports from 2014 to 2023. Descriptive analysis was carried out, while ordinary least square regression was used to test the hypotheses. The findings revealed that firm size has a significant positive effect on cash levels of listed healthcare firms in Nigeria (b = 0.052022; p-value = 0.0260). In conclusion, as firms grow in size, their ability to maintain higher cash balances increases. The study recommends that small healthcare firms should prioritize strategic growth initiatives such as mergers, acquisitions, or market expansion to increase their size and enhance their ability to accumulate and maintain higher cash reserves. This study contributes to knowledge by providing empirical evidence on the relationship between firm size and cash levels in the Nigerian healthcare sector, an area with limited prior research.