Identification and elimination of Muda (any activity adding cost but not value from the customers’ perspective) is one of the main objectives of Lean service. Whilst there is significant research on implementing lean in manufacturing and some service industries, there is little information related to its application to the fast food service industry. The purpose of this paper is to try to fill in this gap by answering the research question: What type of Muda could be identified from the customers’ perspective within the service production processes in the fast food restaurant industry in Spain?

An exploratory case study has been conducted. Three multinational companies were selected and several sites observed in Madrid, Spain. Three methods were used to gather data: document analysis; direct and participative observation and semi-structured interviews.

The paper identifies the seven types of Muda: defects, movements, process, inventory, overproduction, transport and delay. The results are discussed for Cases A, B and C, showing that A and B present higher potential for Muda, compared C.

Threefold value for practitioners and managers: waste identification is an opportunity for non-efficient processes improvement; observation/analysis from the customers’ perspective reveals that customers perceive these inefficiencies; a guideline/audit tool for future assessments.