While public service broadcasters are typically regarded as national institutions, their histories are profoundly transnational. Ideas, programmes, and models have crossed national borders since the earliest days of radio transmission. Yet the transnational histories of radio genres have remained largely unexplored. This article seeks to address that gap by analysing the formation and development of three serial fiction genres—family drama, crime series, and radio comedy—in the context of the Finnish public broadcasting company Yleisradio. Series representing these genres were among the most popular and longest-running radio shows in Finland. Drawing on an extensive collection of empirical material—including Yleisradio’s Annual reports, programming metadata, newspaper clippings, and radio programmes—the research reveals a variety of transnational exchange in programme production. It also underscores the need for further research that places the transnational dynamics at the forefront.