The purpose of the study is to evaluate the clinical effects of Mucosamin® (a spray preparation containing sodium hyaluronate combined with a pool of amino acids of precursor collagen, including L-Proline, L-Leucine, L-Lysine and glycine) on wound healing and pain management of oral mucositis after hematopoietic stem cell transplantation. The importance of professional dental hygiene by dental hygienist in reducing the severity of oral mucositis as unique therapy or in addition to therapy with Mucosamin® was also evaluated. One hundred thirty-seven patients undergoing hematopoietic stem cell transplantation were recruited in a case-control study and divided into 4 groups: Group A: professional oral hygiene + Mucosamin®; Group B: professional oral hygiene + standard treatment with chlorhexidine 0.20%;; Group C: only Mucosamin®; Group D: only standard treatment with chlorhexidine 0.20%. The following evaluations were made: WHO mucositis scale, OMAS mucositis scale, VAS, periodontal recording, days of mucositis. Comparing the groups at the onset of OM on WHO scale, it was observed that Group A grade 1 occurrence was more statistically significant than Group B (p= 0.03*); comparison between Group A and D showed a statistically significant difference in favour of Group A (p= 0.0002*). Also OMAS scale showed a statistically significant difference between groups who assumed Mucosamin, who developed lower OM grade (p = 0.001*). There was a statistically significant difference between group A compared with group B over the overall duration of OM (p = 0.02*), as well as between group A and group D (p=0.03*). According to the present study the combination of a careful debridement, correct oral hygiene during hospitalization and the use of Mucosamin® exponentially reduces the severity and duration of mucositis and consequently the discomfort of the patient. Moreover, it can be stated that the use of Mucosamin® also results in a reduction in the extent of chemotherapy lesions. Hyaluronic acid and amino acid-based sprays can be a valuable therapeutic aid in the treatment of mucositis.