Objective: To verify whether sildenafil is effective in type 1 premenopausal women affected by sexual arousal disorder (SAD). Design: Double-blind, crossover, placebo-controlled study. Setting: Gynecological diabetic outpatient clinic and sexual clinic. Patient(s): Thirty-six type 1 premenopausal diabetic women affected by SAD. Intervention(s): Two 8-week periods of sildenafil 100 mg, washout, and placebo, by two possible sequences. Main Outcomes Measure(s): Each woman submitted blood samples to measure HbA1c, and T, free T (FT), and PRL. Efficacy was assessed [1] subjectively by the Personal Experiences Questionnaire based on the 5-point Likert scale, quantifying arousal, desire, orgasm, enjoyment of sexual activities, and frequency of sexual relationships; and [2] objectively by translabial color Doppler ultrasound to measure the resistance index (RI), pulsatility index (PI), peak systolic velocity (PSV), and end diastolic velocity of clitoral arteries. Result(s): Thirty-two women completed the study. The mean HbA1c value was 8.0% ± 1.8%, and plasma concentrations of T, FT, and PRL were normal. Sildenafil seems to improve arousal, orgasm and sexual enjoyment, and dyspareunia in women affected by type 1 diabetes. However, by flowmetric measurements, the mean RI was significantly lower and both the mean PI and PSV of the clitoral arteries were significantly higher compared with baseline and placebo. Conclusion(s): Sildenafil seems to improve subjective sexual aspects and can be used to treat objectively genital arousal disorder of premenopausal women with type 1 diabetes. [Copyright &y& Elsevier]