Client-public health nurse relationships are considered to be important in nursing literature. However, little research in nursing has touched this area. The purpose of this paper is to describe a study of the patterns of interaction in terms of relationships between clients (mother and child under 1 year of age) and public health nurses in child health care at Finnish health centres. The qualitative data were collected by observing client-public health nurse interactions during visits. In total, 1554 interactions were observed over 2 years from 20 visits to child health centres. The grounded theory method was used in this study. Various relationships were identified between child and mother, child and public health nurse and mother and public health nurse. The relationship between child and mother during the visit was called a tender, protective and persuasive relationship. The relationship between child and public health nurse was called a persuasive and entertainment relationship. The main relationship between mother and public health nurse was called relationship supporting self-confidence. Suggestions for nursing practice and further research are made.