Background Community nurses and general practitioners evaluate their patient-related communication to be poor. However, their actual communication has hardly been investigated and specific strategies for improvement are unclear. Objectives To explore actual community nurse-general practitioner communication in primary care and gain insights into communication style, and conversation structure and their determinants. Methods A mixed-methods design was applied. Telephone conversations between community nurses and general practitioners in the Netherlands were recorded and transcribed verbatim. We measured structure and the duration of their conversations, and community nurses’ self-confidence towards general practitioners and their trust in and familiarity with the conversation partner. A thematic analysis was applied to the transcripts of the conversations. Correlations between these determinants were calculated using Spearman’s correlation coefficient. Results The 18 community nurses recorded 23 conversations with general practitioners. Qualitative analysis revealed that many conversations lacked structure and conciseness, i.e. the nurses started conversations without a clearly articulated question and did not provide adequate background information. The mean duration of their conversations with doctors was 8.8 min. Community nurses with higher self-confidence towards doctors communicated in a more structured way (p = 0.01) and general practitioners were more satisfied about the conversations (p = 0.01). Conclusion This exploratory study of actual community nurse-doctor telephone conversations in primary care identified communication structure and nurse self-confidence towards general practitioners as key targets for the improvement of interprofessional communication, which may increase the effectiveness of community nurse-general practitioner collaboration.