<p>The effects of biological agents on laboratory parameters in patients with psoriasis remain incompletely characterized, with conflicting data reported. To investigate the effects of five biological agents on lipid profiles, hemogram parameters, inflammatory markers, and their correlation with disease activity in psoriasis patients. This retrospective study analyzed hemogram parameters (<i>n</i> = 153) and lipid profiles (<i>n</i> = 124) in psoriasis patients treated with adalimumab, etanercept, infliximab, ustekinumab, or secukinumab for ≥ 6 months. Parameters were evaluated at baseline, week 12, and week 24. Patients with conditions potentially affecting these parameters were excluded. Platelet counts decreased significantly in etanercept and secukinumab groups (<i>p</i> &lt; 0.001, <i>p</i> &lt; 0.05) and all patients (<i>p</i> &lt; 0.001). Lymphocyte counts increased in adalimumab and etanercept groups (<i>p</i> &lt; 0.001, <i>p</i> &lt; 0.01) and all patients (<i>p</i> &lt; 0.001). Neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio decreased significantly in adalimumab, etanercept, secukinumab groups (<i>p</i> &lt; 0.05). Triglyceride levels increased in the ustekinumab group (10.91%) and all patients (3.2%) (<i>p</i> &lt; 0.05). Total cholesterol, LDL, HDL, and atherogenic index showed no significant changes. A strong positive correlation was found between neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio changes (<i>r</i> = 0.646, <i>p</i> &lt; 0.001). Biological agents have specific effects on hematological and lipid parameters in psoriasis patients. The observed changes in inflammatory markers and triglycerides suggest the importance of laboratory monitoring during biological therapy.</p>