Surgical waiting time remains an important issue regarding access to health care provision. It is considered to be excessive in most OEDC countries (over twelve weeks or ninety days). The development of day surgery has been one of the strategies that proved effective in reducing surgical waiting time. This study aims to establish a correlation between surgical waiting time and the percentage of day-surgery cases, in hospitals with surgical services, in the Portuguese National Health Services, during 2006. Methodology: An observational, analytical and ecological study was conducted to establish the correlations existing between surgical waiting time and the percentage of day-surgery procedures realized, as well as associations with other variables, through multivariate and correlation analysis. Results: A negative, statistically significant Spearman’s correlation was observed between the percentage of day-surgery cases and the waiting surgical time for eletive procedures.