Candida is the major fungal pathogen of humans causing a variety of afflictions ranging from superficial mucosal diseases to deep seated mycoses. Opportunistic infections due to Candida species occur frequently in cancer patients because of their inherent immunosuppression. This study aimed to detect the prevalence of oral yeast among Sudanese cancer patients with different cancer patients who received different cancer treatment in Khartoum oncology hospital (al Zarra Hospital). Fifty oral swabs were collected from the patients with different age groups ranging from 10 to 100 old, 18\50 were males and 32\50 were females. The study was carried out in the period from December 2021 to May 2022. All samples were first cultured on to Sabouraoud’s dextrose agar media which was supplemented with penicillin antimicrobial agent, from those only 40% were showed growth. Then growth colonies identified by Gram's stain and sub cultured on chromogenic Candida agar media and inoculated on serum for germ tube test. The colonies gave light green colonies were identified as Candida albicans with (18%), which were the most prevalence strain of isolated Candida species, followed by Candida tropicalis which gave blue colonies with (18%) and then Candida kruzei with (4%) which gave creamy-moove colonies. The study showed that the distribution of an oral yeast among cancer patients was 40% and age group over 50 years old were more affected with an oral yeast. That female was most affected with an oral yeast (64%) (32 female) than male (36%) (18 male). Head and neck cancer (HNC) patient were the most affected group among cancer patients (35%). The study showed that cancer patients that affected with an oral yeast resident out of Khartoum city (66%) compared to those from Khartoum city (34%). Also, the oral yeast infection was high in cancer patients that resident out of hospital (86%) compared patient admitted on the hospital (14%). This study concluded that the frequency of an oral yeast in cancer patients who were received treatment was 40%. The most prevelant species was Candida albicans with 18% which followed by Candida tropicalis 18% and Candida kruzei 4%. Patient in age more than 50 years old were more affected with an oral yeast. The most affected cancer patients were those who were diagnosed with head and neck cancer.