Oral findings of 42 Mexican AIDS patients with cancer were reviewed. Kaposi's sarcoma (KS) was the most frequent malignancy (81%) followed by non-Hodgkin's lymphoma (NHL) (12%). All cases of NHL were of high or intermediate grade and most of them were extranodal. Out of the 34 individuals with KS, 22 (65%) showed oral KS and in 21 of them the palate was involved. The clinical features of oral KS including site, appearance and size are described. Pseudomembranous candidosis (PC), hairy leukoplakia (HL) and exfoliative cheilitis (ECh) were also found in these patients. There was no association of these lesions with any type of cancer. A strong association of oral candidosis and history of this infection was found, RR = 7.0 (1.3-4.1). There was evidence of severe immunosuppression in most patients, with mean average CD4 counts of 116 mm3 (range 4-841/mm3). Oral KS, ECh, PC and HL were more common in patients with lower CD4 counts. Our findings illustrate the most frequent oral lesions associated with HIV-1 infection in patients with AIDS and cancer, and further support the importance of oral examination in HIV infected patients.