The opportunity for the community health nursing profession to engage in international cooperative activities is increasing in recent years. Many challenges are anticipated for developing the cooperative activities, since the basic situations in each country regarding the environment, the cultural background or the health system are quite different. However analysis of the challenges is not enough, we must also understand limitations based on individual personal experiences. The purpose of this report is to describe the challenges that interrupt the development of cooperative activities.
 The target group was sixteen public health nurses who were sent to developing countries as JOCV (Japan Overseas Cooperative Volunteers) from June1997 to March 1999. The research was conducted for two years. Data were collected from each participant using five semi-structured questionnaires and analyzed using qualitative methods for the following areas: (1) challenges, (2) changes in viewpoints about the language learning, and (3) changes in participants' health conditions.
 Fifteen participants returned the questionnaires. Results showed wide variation in the challenges described, and the challenges changed during the period of assignment. During the beginning period, there were many descriptions about difficulties based on daily life and cultural adaptation. Afterward, challenges based on the cooperative activities became the core of issues to resolve. Some challenges involved a lack of information for planning the cooperative activities, lack of funds, a too-short time frame, local staff's resistance to the out-reach activities. Also some issues were very difficult solely on the basis of the personal effort required
 When we carry out cooperative activities in developing countries, there will inevitably be various challenges. However, there are two types of challenges, challenges able to be resolved by personal effort and challenges in need of system responsiveness. To develop effective cooperative activities in a limited period, it is necessary to understand the possible challenges that will happen and take measures to prevent avoidable situations.