Objectives: to identify the occurrence of toxicity associated with chemotherapy and predictors factors of hospitalization, delayed treatment, abandonment, treatment suspension or death. Methods: 126 patients with cancer were in a prospective cohort study, conducted between July/2012 and january/2013, they were interviewed before treatment and after completion of the 1st, 2nd and 3rd cycles, when clinical, demographic and laboratory data were collected. Results: 39,7% had toxicity grade ≥ 3. The latter led to more hospitalization, suspension, delayed treatment and death (p<0,05). Performance status 2 in cycles 1 (p<0,001) and 2 (p=0,025) were risk factors to the toxicity grade ≥ 3. When studied variables prior to first chemotherapy cycle, the body surface area < 1,69 m² was associated with the occurrence of toxicity grade ≥ 3 (p=0,023) and with anemia (p=0,044) and thrombocytopenia (p=0,006) of any grade. Creatinine clearance < 50mL/min was associated with anemia (p=0,032), BMI < 18,5kg/m² with thrombocytopenia (p=0,012), lymphocytes < 1500/mm³ to leukopenia (p=0,017), neutrophils < 3100/mm³ to neutropenia (p=0,002) and leukopenia (p<0,001), all of any toxicity grade. Conclusion: Approximately 40% of patients had toxicity grade ≥ 3, motivating more hospitalization, suspension, delayed treatment and death. Performance status 2 and body surface area < 1,69 m² were related toxicity grade ≥ 3.