Although the IUD is an extremely effective and low-cost contraceptive method, its use has declined sharply in Kenya in the past 20 years. A study tested the effectiveness of an outreach intervention to family planning providers and community-based distribution (CBD) agents in promoting use of the IUD in western Kenya. Forty-five public health clinics were randomized to receive the intervention for providers only, for CBD agents only, for both providers and CBD agents, or no detailing at all. The intervention is based on pharmaceutical companies’ ‘detailing’ models and included education/motivation visits to providers and CBD programmes, as well as provision of educational and promotional materials. District health supervisors were given updates on contraceptives, including the IUD, and were trained in communication and message development prior to making their detailing visits. Detailing only modestly increased the provision of IUDs, and only when both providers and CBD agents were targeted. The two detailing visits do not appear sufficient to sustain the effect of the intervention or to address poor provider attitudes and lack of technical skills. The cost per 3·5 years of pregnancy protection was US$49·57 for the detailing intervention including the cost of the IUD, compared with US$15·19 for the commodity costs of the current standard of care – provision of the injectable contraceptive depot-medroxyprogesterone acetate (DMPA). The effectiveness of provider-based activities is amplified when concurrent demand creation activities are carried out. However, the cost of the detailing in comparison to the small number of IUDs inserted indicates that this intervention is not cost-effective.