This descriptive study was designed to investigate the pelvic floor muscle strength (PFMS) of women aged 18 to 49 years and to examine the factors that may have an effect on PFMS. The study was conducted on 258 women who visited a gynecology outpatient clinic between January 2019 and January 2020, who met the research criteria, and who agreed to participate in the study. The data were collected using the Sociodemographic Characteristics Information Form. The Modified Oxford Scale (MOS) and a perineometer were used to evaluate the PFMS of the women. The mean PFMS value measured using the perineometer was 31.56 ± 12.17 cmH2O (moderate pressure). The PFMS values were 20.00 to 29.9 cmH2O (weak pressure) and 30.00 to 39.9 cmH2O (moderate pressure) in 23.6% of the women, respectively. The PFMS values measured with MOS were of grade 3 strength (moderate pressure) in 23.6% of the women and grade 2 strength (weak pressure) in 23.3%. A statistically significant strong correlation was found between the perineometer measurement and the women’s MOS values. Moreover, a statistically significant difference was found between the PFMS values measured with the perineometer, MOS scores, and women’s age groups, educational status, marital status, employment status, income status, persistent cough, use of nicotine, alcohol and coffee consumptions, chronic constipation, history of frequent urinary tract infections, regular exercise, body mass index, history of pregnancy, mode of delivery, use of episiotomy at birth, perineal rupture at birth, use of forceps vacuum at birth, multiple pregnancies, delivery of a baby weighing ≥4,000 g, treatment during pregnancy, hysterectomy, menopause, frequency of sexual intercourse, and pain during sexual intercourse ( p < .05). We conclude that most of the women in the study had weak to moderate PFMS, that the evaluation of PFMS with the MOS positively overlapped with the perineometric measurements, and that a number of sociodemographic and obstetric variables act as risk factors that affect PFMS. The PFMS of all women should be assessed as part of their routine gynecological examinations.