BACKGROUND: The incidence of tongue cancer is increasing, and survival has not improved since the majority of patients present at an advanced stage. Patient delay has remained the same over the years and is difficult to influence. Much less is known about the delay in diagnosis caused by physicians and dentists. AIM: To investigate the detection of tongue cancer in primary care in Northern Finland and to examine the consultation prevalence of oral symptoms in primary care in Finland. STUDY: Analysis of data from medical records of tongue cancer patients kept between 1 January 1974 and 31 December 1994 for the general health insurance scheme. SETTING: The two northernmost provinces of Finland (population of 700,000). METHOD: Data were collected on demographic and clinical variables and on the first medical visit on 75 tongue cancer patients. In addition, primary care physicians recorded all patient visits during four weeks in 25 health centres randomly selected throughout Finland in 1996. RESULTS: At the initial visit, the tongue cancer patient was correctly referred for further examinations in 49 (65%) cases. In 12 (16%) of cases the patient was not referred but was scheduled for a follow-up visit, and was neither referred nor followed-up in 14 (19%). When compared with the referred patients the median professional delay was somewhat longer for the unreferred patients but increased dramatically if no follow-up was arranged (0.6 months [range = 0.1-2.4] versus 1.2 [range = 0.3-2.2] versus 5.2 [range = 0.7-18.2], P < 0.001). Compared with the referred patients the adjusted relative hazard of death for the non-referred followed-up patients was 1.4 (95% confidence interval [CI] = 0.31-6.5) and that for the non-referred/not followed-up patients 6.3 (95% CI = 1.7-22.9). The high-risk patients included those who sought an early professional evaluation, those who made the appointment for a completely different reason and only mentioned the symptom suggestive of cancer incidentally, those that had a small ulcerative lesion, and blue-collar workers. Oral symptoms were a rare cause of visits (0.55% of all visits) in primary care in Finland. CONCLUSION: Misdiagnosis of tongue cancer at the initial professional evaluation often leads to a fatal delay if the patient is left without any follow-up.