BACKGROUND: Late stage diagnosis of oesophageal and gastric cancer is common, which limits treatment options and contributes to poor survival. AIM: To explore patients' understanding, experience and presentation of symptoms before a diagnosis of oesophageal or gastric cancer. DESIGN & SETTING: Between May 2016 and October 2017, all patients newly diagnosed with oesophageal or gastric cancer were identified at weekly multidisciplinary team meetings at two large hospitals in England. A total of 321 patients were invited to participate in a survey and secondary care medical record review; 127 (40%) participants responded (102 patients had oesophageal cancer and 25 had gastric cancer). Of these, 26 participated in an additional face-to-face interview. METHOD: Survey and medical record data were analysed descriptively. Interviews were analysed using thematic analysis, informed by the Model of Pathways to Treatment. RESULTS: Participants experienced multiple symptoms before diagnosis. The most common symptom associated with oesophageal cancer was dysphagia (n = 66, 65%); for gastric cancer, fatigue or tiredness (n = 20, 80%) was the most common symptom. Understanding of heartburn, reflux and indigestion, and associated symptoms differed between participants and often contrasted with clinical perspectives. Bodily changes attributed to personal and/or lifestyle factors were self-managed, with presentation to primary care prompted when symptoms persisted, worsened, or impacted daily life, or were notably severe or unusual. Participants rarely presented all symptoms at the initial consultation. CONCLUSION: The patient interval may be lengthened by misinterpretation of key terms, such as heartburn, or misattribution or non-recognition of important bodily changes. Clearly defined symptom awareness messages may encourage earlier help-seeking, while eliciting symptom experience and meanings in primary care consultations could prompt earlier referral and diagnosis.