BACKGROUND: Mindfulness interventions to reduce psychological distress are well-suited to pregnancy, due to their brief and non-pharmacological nature, but there is a need for more robust evidence determining their usefulness. This pilot study was designed to explore the feasibility of a randomised controlled trial of a mindfulness intervention to reduce antenatal depression, anxiety and stress. METHODS: The study was designed in two parts 1) a non-randomised trial targeting women at risk of mental health problems (a selected population) and 2) a randomised controlled trial (RCT) of a universal population. Process evaluation focused on feasibility of recruitment pathways, participant retention, acceptability of study measures, and engagement with mindfulness practices. Measurement of psychological distress was taken pre and post intervention through the Centre for Epidemiologic Studies Depression Scale Revised, the Depression Anxiety and Stress Scale-21, the State-Trait Anxiety Inventory, and the Perceived Stress Scale. RESULTS: 20 women were recruited to the non-randomised trial, and 32 to the RCT. Recruitment through a mailed study brochure at the time of booking-in to the hospital resulted in the largest number of participants in the RCT (16/32; 50%), and resulted in considerably earlier recruitment (50% in first trimester, 50% second trimester) compared to recruitment through the antenatal clinic waiting room (86% in second trimester, 14% third trimester). Over a third of women in the universal population scored above clinical cut-offs for depression and anxiety, indicating a sample with more symptomology than the general population. The most common reason for loss to follow-up was delivery of baby prior to follow-up (n = 9). In the non-randomised study, significant within group improvements to depression and anxiety were observed. In the intervention arm of the RCT there were significant within group improvements to anxiety and mindfulness. No between group differences for the intervention and 'care as usual' control group were observed. CONCLUSIONS: This small pilot study provides evidence on the feasibility of an antenatal mindfulness intervention to reduce psychological distress. Major challenges include: finding ways to facilitate recruitment in early pregnancy and engaging younger women and other vulnerable populations. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12613000742774 (31/10/2012).