This paper describes the use of rapid appraisal methods for collecting health data in a poor urban area of Tanzania. During a nine-day field-based workshop with municipal officials rapid appraisal methods were used to collect data and plan interventions in three poor municipal areas. The main technique used was semi-structured interviews with key informants. However, after conducting the interviews it was realised that the participants had no way of assigning any priority to the problems which had been revealed. A second visit had to be made to ask the informants to rank the problems in order of priority. Once the data had been analyzed and priorities for each area identified, the workshop participants considered how to develop a plan of action to respond to the problems. The paper concludes with an assessment of the strengths and weaknesses of the methodology based on this experience.