The purpose of the study is to develop and analyze a content-based needs assessment survey for physics teachers. With this aim, a Teacher Survey on the Nature of Physics (TSNOP) was developed as a measurement instrument for the study. The TSNOP was used to identify inservice physics teachers' needs, wishes, expectations and problems for the Nature of Physics (NOP) unit of a Professional Development Program (PDP). A total of 60 inservice physics teachers participated in the study. TSNOP includes four specific content areas; NOP knowledge and its misconceptions, teaching strategies (methods, techniques), materials and technology, and assessment techniques. The TSNOP consists of structured and unstructured question formats. The survey was analyzed based on dimensions and thematic coding, followed by frequency analysis with data was represented through tables. The TSNOP results are presented and discussed under four dimensions; (a) participant demographics, (b) teachers' previous professional experience, (c) how PDPs can be organized (e.g., type, context, roles, time), and (d) teachers' opinions about the training. Implications for teacher training and professional development were also discussed in the study.