Objective: to evaluate the prevalence and factors associated with tooth loss according to their number and position in cancer patients in southern Minas Gerais, Brazil. Methodology: a cross-sectional study with a sample of 441 adults undergoing cancer treatment. The outcome was obtained by clinical evaluation of tooth loss, categorizing the participants into: (i) having functional dentition (FD) [presence of 20 or more teeth] without anterior losses; (ii) having FD with anterior losses; (iii) not having FD. Independent variables included socioeconomic situation, health-related habits, general and cancer-related health, oral health, and dental care. Bivariate and multiple multinomial logistic regression models were used in data analysis, with (i) as the reference group. Results: 27.29% presented FD without anterior losses; 6.04% had FD with anterior losses; and 66.67% did not have FD. There was a strong possibility of having FD with anterior loss for those who have an income < 1 minimum wage (OR: 0.04; CI95%: 0.01-0.80) and those who did not report flavor alteration (OR: 0.31; IC95%: 0.10-0.90). Individuals with a greater chance of not having FD were older subjects (OR: 1.06; CI95%: 1.02-1.10), less educated (OR: 0.15; CI95%: 0.02-0.81), those who use prosthesis (OR: 63.97; CI95%: 20.22-202.22), those with no periodontal pockets (OR: 0.17; CI95%: 0.07-0.43), and those who brush their teeth < 3x/day (OR: 0.22; IC95%: 0.09-0.53). Conclusion: tooth loss, including anterior losses, has a relevant impact on this population and socioeconomic and oral health conditions are determinants of this outcome.