An increasing part of companies' purchasing expenditures is being spent on (business) services. At the same time, the interactive character of business services has so far largely been neglected in purchasing and supply management studies. The success of a service purchase is however established during the ongoing production and consumption of that service, which takes place in continuous interaction between buyer and seller. This paper investigates these ongoing interactive processes between buyer and seller after the purchase decision has been made. The specific focus is on services buying by manufacturers, since manufacturers' services spend increasingly encompasses services that eventually become part of the final offering to customers. This is expected to pose specific challenges for manufacturing companies, who have traditionally been involved with purchasing goods. Case studies into ongoing buyer–seller interaction are conducted at three manufacturing companies. Starting from a usage-based classification which contains four types of business services, four services are studied at each manufacturing company. The results show that indeed the different types of services can be associated with distinct patterns of ongoing interaction. Furthermore, the results provide initial support for the idea that having differentiated patterns of interaction contributes to successful ongoing service exchange.