Pelvic floor muscle (PFM) are responsible for the involuntary contractions during orgasm. PFM strength has been related to better sexual function and orgasm arousal. However, there is still little evidence on the effects of sex on the contractility of women`s PFM. This study aims to evaluate women PFM strength after immediate sexual intercourse. 41 women with no obstetric past and pelvic floor or sexual dysfunction were included in the study with a mean age of 32 years (SD=6.0) and body mass index 22 (SD=3.9). PFM strength was measured before (without menstruation) and one hour after sexual intercourse and orgasmic climax. Women underwent standardized clinical evaluation with pelvimetre® and Phenix USB2 software. Clitoral and vulvar temperature, blood pressure, heart rate and type of sexual intercourse (partner, masturbation or with dildo) were also recorded. Data analysis was based on Analyses of covariance. No significant differences were shown between PFM strength before and post-sex (p<.05)><.05). Our findings suggest that inmediate sexual intercourse does not influence PFM strength. Further studies in women with perineal pathology may confirm these results.