Pre-existing medical problems have the potential to affect postoperative survival, complications, and health-related quality of life (QoL). Our aim was to explore the relation between past medical history, American Society of Anesthesiologists’ (ASA) score, health-related QoL, and survival. We collected data from 278 consecutive patients with previously untreated oral and oropharyngeal squamous cell carcinoma operated on primarily from 1995 to 1999 inclusive. Past medical history was recorded from the case notes, ASA grade from the anaesthetic record, and QoL was measured using the University of Washington Quality of Life Questionnaire (UW-QoL). Responses to questionnaires were received from (71%) at baseline (63%) at 6 months (73%) at 1 year, and (65%) 18 months or longer. Past medical history was associated with lower ASA scores. At baseline both history and ASA scores were related to the UW-QoL. Longitudinally patients in ASA grade 1 or with no past history scored better in these UW-QoL domains. Past history did not predict survival (P = 0.83), nor did the UW-QoL composite score (P = 0.30), whilst ASA was associated with crude survival (P = 0.003) and disease-specific survival (P = 0.03). When analyses were stratified for adjuvant radiotherapy, type of operation, size of tumour, and age then the relation to ASA was maintained and trends in the past history and UW-QoL remained not significant. ASA, which is often recorded as part of preoperative assessment, reflects both survival and health-related QoL, and is more useful than past history alone for predicting outcome.