Vaginismus is a condition in which involuntary muscle spasm interferes with vaginal intercourse or other penetration of the vagina. This often results in pain with attempts at sex. Often, it begins when vaginal intercourse is first attempted.

The formal diagnostic criteria specifically requires interference during vaginal intercourse and a desire for intercourse. However, the term vaginismus is sometimes used more broadly to refer to any muscle spasms occurring during the insertion of some or all types of objects into the vagina, sexually motivated or otherwise, including the usage of speculums and tampons.

The underlying cause is generally a fear that penetration will hurt. Risk factors include a history of sexual assault, endometriosis, vaginitis, or a prior episiotomy. Diagnosis is based on the symptoms and examination. It requires there to be no anatomical or physical problems and a desire for penetration on the part of the woman.

Treatment may include behavior therapy such as graduated exposure therapy and gradual vaginal dilatation. Surgery is not generally indicated. Botulinum toxin (botox), a muscle spasm treatment, is being studied. There are no epidemiological studies of the prevalence of vaginismus. Estimates of how common the condition is vary. One textbook estimates that 0.5% of women are affected. However, rates in clinical settings indicate that between 5–17% of women experience vaginismus. Outcomes are generally good with treatment.