Background Although there are numerous publications about surgical treatment of proximal humeral fractures (PHFs), few assess conservative treatment, which is the most common approach. The aim of this systematic literature review was to assess criteria for indications, treatment protocols, and outcomes obtained with the conservative treatment of 3-part and 4-part PHF. Methods We searched the PubMed and Cochrane databases for clinical studies published between 2000 and 2019 on conservative treatment for 3-part and 4-part PHF that included patients older than 18 years, a minimum follow-up of 1 year, fracture classification, and description of outcomes with assessment scales. Results The search yielded 26,660 records. We reviewed 44 of them in full, and finally 6 studies were included. We obtained a population of 133 patients (79% women), with a mean age of 74.3 years (range 25 to 98) and mean follow-up of 32 months (range 12 to 68.8). According to the Neer classification system, there were 41% (55) three-part fractures and 59% (78) four-part fractures; 5.81% of the patients were lost to follow-up. The mean Constant score was 64.5 for three-part fractures and 54.9 patients with four-part fractures. Consolidation was achieved in 95% of the three-part fractures and 91% of the four-part fractures. Loss of mobility varied according to the type of fracture. Regarding complications, the most frequent was malunion (21%), followed by avascular necrosis (9%). Conclusions Our data show that most three-part PHFs treated conservatively achieve fracture consolidation even noting a negligible rate of malunion got fair–good functional results with few complications, while the orthopedic four-part PHF treatment presents high rate of consolidation with less rate of malunion than the three-part PHF but achieve poor functional results with few complications. Level of evidence Level IV, Systematic Review