Low socio-economic groups are typically difficult to recruit and retain in health research, which makes it difficult to investigate their health-related beliefs and behaviours. Low socio-economic parents with overweight or obese children took part in a longitudinal qualitative child obesity study over 12 months. These parents' views of and recommendations for appropriate recruitment and retention strategies are reported. Their interpretations and suggestions are considered in the light of the difficulties that were experienced in designing the study to meet their needs and the approaches that were found to be more effective in achieving and maintaining a viable study cohort. Relevant aspects of recruitment included remuneration, recruitment locations and the use of appropriate weight-related terminology. Retention factors included protocol flexibility, ongoing remuneration and learning opportunities. Barriers to ongoing participation are also discussed. Suggestions are provided for future qualitative research with low socio-economic families.