Mathematics educators have had a long standing interest in students' understanding of decimal numbers. Most studies of students' understanding of decimals have been conducted within Western cultural settings. Similar research in other countries is important for a number of reasons, perhaps most importantly because it can provide insights that may benefit the mathematical learning of all students. The present study sought to gain insight into Chinese Hong Kong students' and regional Australian students' general performance on a variety of decimals tasks. These tasks included: comprehending place value after the decimal point; the proper use of algorithms for computation of decimals; and the application of decimals to "real life" problems. More specifically, it aimed to investigate students' error patterns. The study also aimed to investigate Chinese Hong Kong students' and Australian students' procedural and conceptual understanding of decimals. The results indicated that for many of the questions, Hong Kong and Australian students shared similar misconceptions. For others, Hong Kong students exhibited stronger procedural and conceptual understanding of the task.