Despite the evidence base for Internet-delivered self-help programmes, their application to cancer carers has not been reported. This feasibility study evaluated a 6-week internet cognitive behaviour therapy (CBT) programme for early stage cancer carers. The study participants comprised 13 carers who were recruited over a 17-month period. Measures included distress, quality of life and programme engagement. Changes over time were measured using effect sizes (Cohen's d), whereas acceptibility was assessed using qualitative feedback. Low enrolment and high attrition rates resulted in a failure to demonstrate feasibility. Large improvements in negative affect (d≤0.88) and emotional functioning (d≤0.62) were found. For treatment completers, the intervention holds promise in reducing distress. However, in light of the serious challenges with recruitment and retention, further research is needed to resolve participation barriers.