Introduction. Premature ejaculation (PE) is a prevalent, yet often underdiagnosed, sexual disorder that affects men of all ages. Identification of PE is hampered by stigma and embarrassment associated with the condition, and limited awareness that it is treatable. Because diagnosis informs treatment decisions that have an impact on clinical outcomes, the ability to diagnose PE accurately is vital to the successful management of this condition. Aim. Provide an overview of how to evaluate and diagnose PE. Methods. Review of the literature. Main Outcome Measures. The taxonomy of PE based on onset, time, type, and comorbidities. Results. Diagnosis of PE encompasses seven key steps: (i) Obtaining the patient's general medical and sexual history; (ii) Classifying the symptom on the basis of onset (e.g., lifelong or acquired PE), timing (e.g., prior to or during intercourse), and type (e.g., absolute/generalized or relative/situational); (iii) Involving the partner to determine their view of the situation and the impact of PE on the couple as a whole; (iv) Identifying sexual comorbidities (e.g., erectile dysfunction) to define whether PE is simple (occurring in the absence of other sexual dysfunctions) or complicated (occurring in the presence of other sexual dysfunctions); (v) Performing physical examination to check the man's sexual organs and reflexes; (vi) Identifying underlying etiologies and risk factors (e.g., endocrine-, urological-, or psychorelational-/psychosexual-related) to determine the primary cause of PE and any associated comorbidities; (vii) Discussing treatment options to find the most suitable intervention, according to the needs of the man and his partner. Conclusion. A greater understanding of how to diagnose PE correctly, and a more widespread use of a structured diagnostic approach, could lead to better treatment outcomes in the future. Jannini EA, Maggi M, and Lenzi A. Evaluation of premature ejaculation. J Sex Med 2011; 8(suppl 4): 328-334.