51 Eridani observations were performed with the VLT exoplanet imager SPHERE for 3 years in order to monitor the orbital motion of the known giant planet and refine its orbital parameters. We carried out an orbital analysis using three complementary approaches (LSMC, MCMC, Bayesian rejection sampling) and found broadly similar results. The data suggest a period of 23-49yr (i.e. semi-major axis of 10-16au), an inclination of 126-147{deg}, an eccentricity of 0.30-0.55, and an argument at periastron of 57-121{deg} (mod 180{deg}). The time at periastron and the longitude of node exhibit bimodal distributions.
