ObjectiveDue to the lack of psychometric studies using the Massachusetts General Hospital-Sexual Functioning Questionnaire (MGH-SFQ) in Spain, its Spanish validation is proposed in the present study, by analysing its reliability and validity. DesignCross-sectional descriptive study. SettingGeneral population. Conducted in 20 provinces. ParticipantsThe sample consisted of 3,050 participants (45.41% men and 54.59% women) and was selected using a quota convenience sampling procedure. They ranged in age from 18 to 83 years-old (M=41.51; SD=13.45). Main measurementsSpanish versions of the MGH-SFQ, Sexual Assertiveness Scale, Sexual Desire Inventory, and Index of Sexual Satisfaction. ResultsThe MGH-SFQ showed a single dimensional structure, which explained 71.35% of variance in men and 83.56% in women. Reliability values were .90 and .93, respectively. Convergent validity was adequate as their scores were positively correlated to initiation sexual assertiveness, dyadic sexual desire, and sexual satisfaction. The MGH-SFQ identified that females showed more sexual dysfunctions than males, and detected more sexual dysfunctions as age increases. ConclusionsThe Spanish validation of the MGH-SFQ is a reliable and valid self-reporting questionnaire to assess sexual dysfunctions in Spain. Its psychometric goodness of fit, together with its brevity and ease of use, make it a useful instrument to detect overall, as well as particular sexual dysfunctions.