To report on the prevalence of different types of breast-milk substitutes (BMS) marketing and the compliance of such marketing with the ‘Control of Marketing of Infant and Young Child Food Act 2017’ (The Act) and the ‘International Code of Marketing of Breast-milk Substitutes (WHO Code)’ in Thailand.

Cross-sectional quantitative study, guided by the WHO/UNICEF NetCode Periodic Assessment Protocol.

Health facilities and retail outlets in Bangkok, Thai media.

Mothers of 0–2-year-old children, health professionals, promotions at retail outlets and health facilities, product labels, marketing on television and the internet.

Marketing to mothers was highly prevalent, mostly from electronic or digital media, while BMS companies provided items to health professionals to distribute to mothers. Promotional materials in health facilities displayed company brands or logos. At retail outlets, most promotions were price-related. Approximately two-fifths of labels contained nutrition or health claims. Television marketing was growing-up-milk (GUM) advertisements, while internet promotions were varied from price-related materials to product reviews. Most instances of non-compliant BMS marketing with the Act were advertisements to mothers, and most were infant formula. Most non-compliant BMS marketing with the WHO Code was mainly concerned GUM, which are not covered by the Act and appeared in the media.

BMS marketing does not fully comply with the Act or the WHO Code. The Thai government should conduct regular monitoring and enforcement activities, educate health professionals, and strengthen the Act’s provisions on the media and GUM to fully align with the WHO Code.