This paper describes the design and testing of the rendezvous GNC for the HERACLES Lunar Ascent Element (LAE). The LAE needs to carry samples from the lunar surface to the Lunar Orbital Platform – Gateway (LOP-G) from where the samples are eventually transported back to Earth. The GNC design integrates the GNC for the launch and ascent, the orbit transfer manoeuvres and rendezvous in a near-rectilinear halo orbit (NRHO) into a single simulator. The main focus of this paper is on the consolidated Monte Carlo simulation test campaign results, in particular the rendezvous phase. A discussion of the results and an analysis of the dependence of the results on the assumptions made to define the scenario is performed. The results show that the current design for the GNC is feasible and that the HERACLES LAE mission to the LOP-G can be successfully performed.