Objectives: to analyze the mean direct cost and peripheral venous access length outcomes using devices over needle with and without extension. Methods: quantitative, exploratory-descriptive research. Venous punctures and length of the devices were followed. The mean direct cost was calculated by multiplying the time (timed) spent by nursing professionals by the unit cost of labor, adding to the cost of materials. Results: the total mean direct cost of using devices “with extension” (US$ 9.37) was 2.9 times the cost of using devices “without extension” (US$ 4.50), US$ 7.71 and US$ 2.66, respectively. Totaling 96 hours of stay, the “device over needle with extension” showed a lower occurrence of accidental loss. Conclusions: the use of the “device over needle with extension”, despite its higher mean direct cost, was more effective in favoring adequate length of peripheral venous access.