Medullary thyroid cancer (MTC) accounts for about 2% of all thyroid cancer, but has a relatively poor prognosis compared with differentiated thyroid cancer. Anlotinib is a novel multitarget tyrosine kinase inhibitor targeting VEGFR, PDGFR, FGFR and c-Kit. This multicenter, randomized, double-blind, placebo-controlled phase ⅡB study (ALTER 01031, NCT02586350) was conducted to investigate the efficacy and safety of anlotinib in MTC. Patients with histopathologically confirmed, unresectable locally advanced or metastatic MTC were enrolled and randomly assigned in a 2:1 ratio to receive anlotinib (12mg once daily from day 1 to 14 every 3 weeks) or placebo. Patients in placebo group were allowed to receive open-label anlotinib after disease progression. The primary end point was progression-free survival (PFS); secondary end points included objective response rate (ORR), disease control rate (DCR), and overall survival (OS). 91 patients were enrolled. At data cutoff date, the median PFS was significantly prolonged in anlotinib group than in placebo group (20.7 months vs. 11.1 months, P = 0.029, HR = 0.53 [95% CI, 0.30-0.95]). The ORR of anlotinib treatment was 48.4%. The incidence of treatment related adverse events (TRAE) was 100% and 89.7% in anlotinib and placebo groups. The most common TRAE of all grades in the anlotinib group were palmar-plantar erythrodysesthesia syndrome (62.9%), proteinuria (61.3%) and hypertriglyceridemia (48.4%). Anlotinib demonstrates its efficacy and safety in this phase ⅡB trial for the treatment of MTC and may become a new choice for this rare disease, especially for Chinese patients. Copyright ©2021, American Association for Cancer Research.