The relationship between vection (illusory self-motion) and cybersickness is complex. This pilot study examined whether only unexpected vection provokes sickness during head-mounted display (HMD) based virtual reality (VR). 20 participants ran through the tutorial of Mission: ISS (an HMD VR app) until they experienced notable sickness (maximum exposure was 15 minutes). We found that: 1) cybersickness was positively related to vection strength; and 2) cybersickness appeared to be more likely to occur during unexpected vection. Given the implications of these findings, future studies should attempt to replicate them and confirm the unexpected vection hypothesis with larger sample sizes and rigorous experimental designs. vection is more likely to occur and be more compelling when the self-motion is expected, anticipated or primed [4–6], unexpected vection and its effects during HMD VR have received little examination. This exploratory pilot study examined the proposal that only unexpected vection provokes cybersickness.