Objectives This study reports the development of the AUT-EZ-ME, a new diagnostic instrument in order to quickly, reliable, and valid identify and differentiate children with autism aged 4-18 years. Methods A total of 216 parents of children age 4 to 18 years participated in this study and were divided into three groups: children with autism, children without any diagnosis, and children with other diagnosis. The participants were asked to complete the AUT-EZ-ME which could be administered online. The AUT-EZ-ME is a 36-item parent report questionnaire based on the empathizing-systemizing theory. The questionnaire consists of a series of descriptive statements designed to assess three main features of autism and the eleven associated areas as shown in previous research: social skills, attention switching, attention to detail, communication, imagination, recognition of emotions, sharing of emotional states, perspective taking, narrow interests, repetitive behavior, and resistance to change or need for sameness. Results A very clear differentiation was found between children with autism and the typical group and the other diagnosis groups using the AUT-EZ-ME. Furthermore, we found a good internal consistency of the AUT-EZ-ME and its belonging subscales. Conclusions The AUT-EZ-ME is found to be a reliable and valid diagnostic tool for the identification of children with autism. The AUT-EZ-ME showed satisfactory internal consistency and high sensitivity together with low specificity when a cut-off score is set at 26.