The purpose of this prospective cohort study was to determine if hamstring tightness was an increased risk in plantar fasciitis. It was thought that there is an increased risk of plantar fasciitis when hamstring tightness is present. A total of 105 patients (68 women, 37 men) were included in the study, 79 of whom were diagnosed with plantar fasciitis. Body mass index (BMI) was calculated and the presence of plantar fasciitis, equinus, and calcaneal spurs were assessed. The popliteal angle was measured using standard diagnostic techniques. Without controlling for covariates, BMI, the presence of a calcaneal spur, tightness in the gastrocnemius, gastrocnemius-soleus, and hamstring all had statistically significant association with plantar fasciitis. After controlling for covariates, patients with hamstring tightness were about 8.7 times as likely to experience plantar fasciitis (P < .0001). Patients with BMI >35 were approximately 2.4 times as likely to experience plantar fasciitis compared with those with BMI <35 (P = .04). This study demonstrates that hamstring tightness plays a significant role in the presence of plantar fasciitis and should be addressed along with equinus and obesity when providing treatment to patients with this diagnosis.