Aim: To identify clinical and inflammatory factors associated with adequate haemoglobin control among patients receiving maintenance haemodialysis and erythropoiesis-stimulating agent (ESA) therapy. Methods: This analytical cross-sectional study included 100 adults receiving maintenance haemodialysis. Among 80 patients receiving ESA therapy, adequate haemoglobin control was defined as haemoglobin ≥ 100 g/L and inadequate control as haemoglobin < 100 g/L at the cross-sectional assessment; 20 patients not receiving ESA therapy were described separately. Clinical characteristics and laboratory measurements, including C-reactive protein (CRP), were recorded. The erythropoietin resistance index (ERI) was calculated from weekly ESA dose, body weight, and haemoglobin concentration. Results: Eighty patients (80.0%) received ESA therapy, while 20 (20.0%) did not. Among ESA-treated patients, longer haemodialysis vintage was associated with higher odds of adequate haemoglobin control (OR = 1.02, 95% CI 1.01–1.04), whereas higher CRP was associated with lower odds (OR = 0.90, 95% CI 0.83–0.99). ERI was inversely associated with adequate control (OR = 0.004, 95% CI 0.001–0.066), although this finding is mathematically coupled to the haemoglobin-based outcome. The exploratory model was statistically significant (χ² = 45.4; p < 0.001). Conclusion: Longer haemodialysis vintage and lower CRP were associated with adequate haemoglobin control during ESA therapy. ERI findings require cautious interpretation because haemoglobin is included in the ERI denominator and was also used to define the outcome.