BACKGROUND: Psychological distress, defined as depression, anxiety and perceived stress, during pregnancy is common, with 15-25% of women experiencing clinically significant levels of such distress. Despite the far-reaching impact of prenatal psychological distress on mothers and their children, and that women are receptive to screening, few providers routinely screen for prenatal psychological distress and less than one in five women will receive the mental health care that they require. There is a lack of certainty regarding the most effective treatments for prenatal psychological distress. No online interpersonal psychotherapy (IPT) trials have been conducted that focus on improving psychological distress in prenatal women. The purpose of this pilot randomized controlled trial is to evaluate the perspectives of pregnant women on the feasibility and acceptability of online IPT (e-IPT) delivered during pregnancy. METHODS: A pilot randomized controlled trial design with repeated measures will evaluate the feasibility and acceptability of e-IPT for pregnant women compared to routine prenatal care. Qualitative interviews with 15-30 individuals in the intervention group will provide further data on the feasibility and acceptability of the intervention. Assessment of feasibility will include the ease of accessing and completing the intervention. Women will also be asked about what barriers there were to starting and completing the e-IPT. Assessment of acceptability will inquire about the perception of women regarding the intervention and its various features. A sample size of 160 consenting pregnant women aged 18 years and older will be enrolled and randomized into the experimental (e-IPT) or control (routine care) condition. The secondary outcome measures include: depression, anxiety and stress symptoms; self-efficacy; self-mastery; self-esteem; relationship quality (spouse, immediate family members); coping; and resilience. All participants will complete the aforementioned measures at baseline during pregnancy (T1), 3 months postrandomization (T2), at 8 months of pregnancy (T3), and 3 months postpartum (T4). DISCUSSION: The results of this pilot randomized controlled trial will provide data on the feasibility and acceptability of the intervention and identify necessary adaptations. This study will allow for optimization of full trial processes and inform the evaluation strategy, including sample size calculations for the full randomized controlled trial. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01901796. Registered on 18 December 2014.