ObjectiveTo explore the infection status and clinical characteristics of healthcareassociated infection(HAI) in patients initially diagnosed with multiple myeloma(MM) during the induction period. MethodsClinical data of 116 patients diagnosed with MM and initially treated with PAD(bortezomib+adriamycin+dexamethasone) or PDD(bortezomib+liposome doxorubicin+dexamethasone) regimen in a hospital were collected, infection rates and clinical characteristics of patients during the induction therapy period were analyzed statistically. ResultsAmong 116 patients, 69 received PAD regimen, and 47 received PDD regimen, infection rates in two groups were 79.7% and 89.4% respectively; 73 patients received subcutaneous injection of bortezomib, 43 received intravenous injection of bortezomib, infection rates in subcutaneous injection group and intravenous injection group were 78.1% and 93.0% respectively，difference was statistically significant between two groups(P<0.05). During the induction period, HAI rate was 83.6%（n=97），81 patients developed infection during the first course, infection status of 3 patients were not clear due to therapy outside the hospital, the actual infection rate was 71.7% (81/113); infection rate during the second course was 56.6%（64/113）；a total of 98 patients completed three therapy courses, infection rate was 43.9%（43/98）；66 patients completed four therapy courses, infection rate was 28.8%(19/66). With the increase of the therapy course, infection rate showed a downward trend. Infection sites from high to low were respiratory system, skin and mucosa, oral and gastrointestinal system, bloodstream, and urinary tract. Difference in constitute of clinical diagnosis between patients receiving and without receiving prophylactic antifungal agents during chemotherapy period was not statistically significant （P=0.063）. ConclusionInfection rate is very high during induction period, the main infection site is respiratory system, clinicians and patients need to pay more attention to the prevention and treatment of respiratory system infection.