To find the sort of information given to cancer patients in PC and the factors which affect the disclosure of the diagnosis.A descriptive crossover study, carried out through a personal interview.A county hospital with no oncology service.All those patients with cancer (histologically confirmed) admitted to the hospital during April and May 1993.Each patient was asked what illness he/she had, who told him/her and where, along with his/her sociodemographic details. Later the date of diagnosis and the site and spread of the tumour were taken from the medical records. Out of 108 patients under study, 8 knew they had cancer, 1 said he/she had a tumour and 11 believed they had "something bad". 7 patients had no information about their illness and 81 gave alternative diagnoses (inflammation, cyst...). Disclosure was more common in the cases of breast cancer, haematological cancer and those diagnosed over 6 months previously. No significant differences regarding the spread of the tumour or the sociodemographic variables were found.The disclosure of a diagnosis of cancer is the exception, not the rule. Concealment is only abandoned in the case of potentially curable tumours and those which offer a longer life expectancy.