In this paper, we compare the impact that standing and seated viewing of 360 degrees videos on head-mounted displays has on subjective quality assessment. The statistical analysis of the data gathered in a pilot study is reported in terms of average rating times, mean opinion scores, and simulator sickness scores. The results indicate: (1) Average rating times consumed for 360 degrees video quality assessment are similar for standing and seated viewing, (2) Higher resolving power among different quality levels is obtained for seated viewing, (3) Simulator sickness is kept significantly lower when seated.