Background Over-use and misuse of antibiotics are major causes of antibiotic resistance. This study explored the understanding and reported use of antibiotics amongst three ethnic groups in New Zealand. Methods Questionnaire survey of 300 Indian, Egyptian, and Korean people. Results Most people (73.3%) knew that antibiotics killed bacteria, but other incorrect responses were also common. A range of medicines were mistakenly identified as antibiotics. Nearly half the sample (43.3%) believed colds and flu were caused by bacteria. Only 45.4% were sure that antibiotics were not useful for colds and flu. A minority of participants knew about antibiotic resistance. There were significant differences between groups, with Koreans having lower levels of understanding. Discussion Interventions to improve use of antibiotics need to be pitched at a very basic level of knowledge, and need to be targeted towards particular ethnic groups, particularly those in whose home countries antibiotics are widely available without prescription.