This chapter develops an approach to the socio-material composition of temporality in healthcare, emphasising how time is configured through the interplay of social, technical, and material elements. Challenging the dominant view of time as a linear, external measure, it introduces the concept of “sensitive trajectories”, which frames temporality as a relational and emergent product of healthcare mundane practices. This approach, informed by Puig de la Bellacasa’s notion of “matters of care”, suggests that the alignment of temporalities in healthcare is fragile and requires effort. Being based on a case study of the last major health reform in Chilean healthcare system—the Explicit Health Guarantees regime—and material generated primarily through focused ethnographies, the chapter exemplifies how diverse entities and practices—such as patients, healthcare professionals, meetings, and non-human agents like databases and e-mails—subtly configure different temporal flows in health political design and clinical settings, revealing the precariousness of these temporal alignments, which are constantly threatened by disruptions and require ongoing maintenance. By positioning time as an active agent shaped by these relations, we highlight the need to care for temporality in healthcare, exposing time as a fragile, co-produced phenomenon that emerges from the everyday work of assembling heterogeneous elements.