Patients undergoing chemotherapy may develop erythema, mucositis, ulcerations of the oral mucosa, bleeding upon minor trauma, stomatitis, severe pain, xerostomia and rampant caries. It can also cause myelosuppression and delay in oral mucosa healing. To prevent these side effects, a patient-oriented dental protocol was applied before chemotherapy, including meticulous dental and oral hygiene instructions, scaling and root planning, extraction of hopeless teeth, caries removal and caries prevention. The medical records of 52 dentulous patients (mean age 56.2 y) who received pretreatment were compared to 35 patients (mean age 55.22 y) without any pretreatment before chemotherapy. There was no gender predilection between groups. In the treated group, 13 patients were treated with CMF, 14 with CAF, 8 with 5-FU+folinic acid, 10 with taxane-based treatments and 7 with other chemotherapy treatment. Oral complications were evident in 6 patients (12%). The most frequent complication was mucositis (66%). During chemotherapy 12 patients (23%) needed local oral intervention. In the untreated group, 11 patients were treated with CMF, 12 with FUFA, 4 with CAF, and 5 with other chemotherapy treatment. No oral side effects were found in 13 patients (37.14%), 10 (28.57%) needed local oral intervention, in 10 patients (28.57%) chemotherapy was delayed until side effects were treated and in 2 patients (5.71%) chemotherapy was interrupted and dosage lowered prior chemo retreatment. From the patient files 5 had dental complication per-se, but were not treated at our clinic. Mucositis was the most frequent complication in the untreated group and was more severe than in the treated group. Chemotherapy causes oral complications and side effects. The safety effectiveness as well as patient well being may be dramatically improved by the application of pre-chemotherapy dental protocol.