BACKGROUND This retrospective study aimed to compare the roles of hand and wrist ultrasound in diagnosing subclinical synovitis in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) at a single center in Sichuan, China. MATERIAL AND METHODS Forty-one patients with SLE and 20 patients with RA were included. SLE was diagnosed using the American rheumatology Society (ACR) classification standard. Severity of SLE was evaluated using the SLE disease activity index (SLEDAI). General and clinical manifestations and laboratory indicators were measured. Spearman correlation analysis was used for analyzing correlations between musculoskeletal ultrasound results and indexes. RESULTS Among 41 patients with SLE, 26 (63.4%) had joint pain, and 39 (95.1%) had at least 1 joint abnormality. Thirteen patients with SLE (31.7%) had wrist joint involvement, 7 (17.1%) had metacarpal phalangeal-1 (MCP1) involvement, 8 (19.5%) had MCP2 involvement, 17 (41.5%) had MCP3 involvement, 14 (34.1%) had MCP4 involvement, and 5 (12.2%) had MCP5 involvement. Meanwhile, 2 (4.8%) had proximal interphalangeal-1 (PIP1) involvement, 10 (24.4%) had PIP2 involvement, 17 (41.5%) had PIP3 involvement, 12 (29.3%) had PIP4 involvement, and 3 (7.3%) had PIP4 involvement. Twelve patients demonstrated knee joint involvement. MCP joints had the highest involvement frequency (P=0.003). The most frequently detected disease was synovitis, followed by tenosynovitis, joint effusion, and bone erosion. ESR (P=0.002), CRP (P=0.020), and SLEDAI (P=0.011) of patients with SLE with arthralgia were significantly higher compared to patients without arthralgia. In patients with RA, musculoskeletal ultrasound scores were correlated with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), disease activity score-28 (DAS28), and interleukin-6 (IL-6). In patients with SLE, musculoskeletal ultrasound scores were correlated with double-stranded DNA (dsDNA), ribonucleoprotein (RNP), DAS28, and IL-6. CONCLUSIONS Musculoskeletal ultrasound is highly sensitive in evaluating subclinical synovitis in patients with SLE, and its score is positively correlated with dsDNA, RNP IL-6, and DAS28 in patients with SLE.