The purpose of this study was to examine collaboration relating to public health nursing in different sized Norwegian municipalities. It sought to gain insight into factors that are important for successful collaboration, frequency of meeting points for collaborating activities and missing professionals in different sized municipalities. A cross-sectional e-post questionnaire study was carried out on a national sample of public health nurses and their collaborators. A total of 849 public health nurses (43.64%), 113 doctors at clinics and school health services (54.8%), 519 child protection workers (16.34%) and 115 midwives (41.3%) returned the questionnaire. The data were analysed using descriptive and inferential statistics. Analysis of variance (anova), Kruskal-Wallis H and chi-square tests were used to tests differences between groups. Trust, respect and collaborative competence were ranked highest by all the respondents and formalised structures, economy and leadership ranked least important in collaborative activity. The majority of the respondents stated that they do not have fewer meeting points compared with 5 years ago. Collaboration with mental health services was missed most by all respondents. There were associations between frequency of meeting points and statements on collaboration related to municipality size. Norway is in the throes of a major coordination reform. The fact that relational factors were deemed most important for successful collaboration is an important finding at a time when focus is on structural change. The findings indicate the need for further in depth qualitative studies on reasons for 'missing collaborators,' on professional cultures in different sized municipalities and on interpersonal relationships. Qualitative enquiry is necessary to gain a greater understanding of how relational concepts of respect, trust and conflict are understood by municipal public health professionals.