Background: Proper isolation and restoration of class V subgingival cavities are technique sensitive, thus the resin composite restoration is liable to contamination. This in vitro study was conducted to evaluate the surface microhardness and compressive strength of bulk-fill flowable resin composite after being contaminated during its packing.Materials and methods: Resin composite discs were prepared using split mold. The contaminated specimens were allocated into four groups (n=20) according to the contaminant used: hemostatic agent (Group 1), alcohol (Group 2), artificial saliva (Group 3) and powdered gloves (Group 4). The non-contaminated specimens (n=20) were used as control group. The surface microhardness and compressive strength of each group were tested one-day post-photocuring (n=5) and one-month post-photocuring (n=5). Values were presented as mean, standard deviation (SD) values and confidence intervals. Results: At one-day and one-month post-photocuring, the highest surface microhardness mean values were recorded in control groups. The difference between all groups was statistically insignificant at one-day post-photocuring (p=0.299) and at one-month post-photocuring (p=0.880). The highest compressive strength mean values at one-day and one-month post-photocuring were recorded in control groups (110.42 MPa and 172.87 MPa respectively), followed by alcohol groups, then hemostatic agent groups, followed by artificial saliva with the least value recorded in powdered gloves groups (56.71 MPa and 49.5 MPa respectively). Conclusions: Contamination of bulk-fill flowable resin composite with hemostatic agent, alcohol, artificial saliva, or powdered gloves during its packing decreased its compressive strength at one-day and one-month post-photocuring; but did not affect its surface microhardness.Clinical Relevance:The findings confirmed that resin composite packing is a technique-sensitive procedure where any negligence contributing to resin composite contamination could lead to decrease of its mechanical properties.