Fused Deposition Modelling (FDM) 3D printing technology has become popular for producing prototypes and final parts in various industries, including the automotive, aerospace, and medical sectors. The leakage of such components is often an important factor in determining their possible applications. This paper focuses on researching the influence of printing parameters on leakage and relating the results to the strength of parts produced using this technology. The printing parameters considered were temperature and layer height. PLA (polylactic acid) was chosen as the material due to its biodegradability and biocompatibility. Leakage measurements were carried out using an empty cylinder-shaped vessel filled with air under pressure. The leakage value was observed as a pressure drop over time. It was shown that 3D-printed FDM vessels are not perfectly leak-proof, but the value of observed leakage may be acceptable for selected applications (leakage below 2.5 Pa/s). The results showed a high correlation be-tween the height of the printed layer in both the leakage and strength of the tested samples, while reducing the height increased the tightness and strength of the 3D-printed parts. The effect of printing temperature was less significant.